Installation failed, reverting ./composer.json to its original content.

[prashantkambar]

Problem 1
- The requested package opentok/opentok No version set (parsed as 1.0.0) is satisfiable by opentok/opentok[No version set (parsed as 1.0.0)] but these conflict with your requirements or minimum-stability.
Problem 2
- phpunit/phpunit 5.7.9 requires ext-dom * -> the requested PHP extension dom is missing from your system.
- phpunit/phpunit 5.7.8 requires ext-dom * -> the requested PHP extension dom is missing from your system.
- phpunit/phpunit 5.7.7 requires ext-dom * -> the requested PHP extension dom is missing from your system.
- phpunit/phpunit 5.7.6 requires ext-dom * -> the requested PHP extension dom is missing from your system.
- phpunit/phpunit 5.7.5 requires ext-dom * -> the requested PHP extension dom is missing from your system.
- phpunit/phpunit 5.7.4 requires ext-dom * -> the requested PHP extension dom is missing from your system.
- phpunit/phpunit 5.7.3 requires ext-dom * -> the requested PHP extension dom is missing from your system.
- phpunit/phpunit 5.7.27 requires ext-dom * -> the requested PHP extension dom is missing from your system.
- phpunit/phpunit 5.7.26 requires ext-dom * -> the requested PHP extension dom is missing from your system.
- phpunit/phpunit 5.7.25 requires ext-dom * -> the requested PHP extension dom is missing from your system.
- phpunit/phpunit 5.7.24 requires ext-dom * -> the requested PHP extension dom is missing from your system.
- phpunit/phpunit 5.7.23 requires ext-dom * -> the requested PHP extension dom is missing from your system.
- phpunit/phpunit 5.7.22 requires ext-dom * -> the requested PHP extension dom is missing from your system.
- phpunit/phpunit 5.7.21 requires ext-dom * -> the requested PHP extension dom is missing from your system.
- phpunit/phpunit 5.7.20 requires ext-dom * -> the requested PHP extension dom is missing from your system.
- phpunit/phpunit 5.7.2 requires ext-dom * -> the requested PHP extension dom is missing from your system.
- phpunit/phpunit 5.7.19 requires ext-dom * -> the requested PHP extension dom is missing from your system.
- phpunit/phpunit 5.7.18 requires ext-dom * -> the requested PHP extension dom is missing from your system.
- phpunit/phpunit 5.7.17 requires ext-dom * -> the requested PHP extension dom is missing from your system.
- phpunit/phpunit 5.7.16 requires ext-dom * -> the requested PHP extension dom is missing from your system.
- phpunit/phpunit 5.7.15 requires ext-dom * -> the requested PHP extension dom is missing from your system.
- phpunit/phpunit 5.7.14 requires ext-dom * -> the requested PHP extension dom is missing from your system.
- phpunit/phpunit 5.7.13 requires ext-dom * -> the requested PHP extension dom is missing from your system.
- phpunit/phpunit 5.7.12 requires ext-dom * -> the requested PHP extension dom is missing from your system.
- phpunit/phpunit 5.7.11 requires ext-dom * -> the requested PHP extension dom is missing from your system.
- phpunit/phpunit 5.7.10 requires ext-dom * -> the requested PHP extension dom is missing from your system.
- phpunit/phpunit 5.7.1 requires ext-dom * -> the requested PHP extension dom is missing from your system.
- phpunit/phpunit 5.7.0 requires ext-dom * -> the requested PHP extension dom is missing from your system.
- Installation request for phpunit/phpunit ~5.7 -> satisfiable by phpunit/phpunit[5.7.0, 5.7.1, 5.7.10, 5.7.11, 5.7.12, 5.7.13, 5.7.14, 5.7.15, 5.7.16, 5.7.17, 5.7.18, 5.7.19, 5.7.2, 5.7.20, 5.7.21, 5.7.22, 5.7.23, 5.7.24, 5.7.25, 5.7.26, 5.7.27, 5.7.3, 5.7.4, 5.7.5, 5.7.6, 5.7.7, 5.7.8, 5.7.9].

To enable extensions, verify that they are enabled in your .ini files:
- /etc/php/7.0/cli/php.ini
- /etc/php/7.0/cli/conf.d/10-opcache.ini
- /etc/php/7.0/cli/conf.d/10-pdo.ini
- /etc/php/7.0/cli/conf.d/20-calendar.ini
- /etc/php/7.0/cli/conf.d/20-ctype.ini
- /etc/php/7.0/cli/conf.d/20-exif.ini
- /etc/php/7.0/cli/conf.d/20-fileinfo.ini
- /etc/php/7.0/cli/conf.d/20-ftp.ini
- /etc/php/7.0/cli/conf.d/20-gettext.ini
- /etc/php/7.0/cli/conf.d/20-iconv.ini
- /etc/php/7.0/cli/conf.d/20-json.ini
- /etc/php/7.0/cli/conf.d/20-phar.ini
- /etc/php/7.0/cli/conf.d/20-posix.ini
- /etc/php/7.0/cli/conf.d/20-readline.ini
- /etc/php/7.0/cli/conf.d/20-shmop.ini
- /etc/php/7.0/cli/conf.d/20-sockets.ini
- /etc/php/7.0/cli/conf.d/20-sysvmsg.ini
- /etc/php/7.0/cli/conf.d/20-sysvsem.ini
- /etc/php/7.0/cli/conf.d/20-sysvshm.ini
- /etc/php/7.0/cli/conf.d/20-tokenizer.ini
You can also run php --ini inside terminal to see which files are used by PHP in CLI mode.