Ubuntu 16.04LTS support

[trycoon]

It would be nice if the Dockerfile gets updated to the latest Ubuntu 16.04 LTS version.
Some packages also seems obsolete:
E: Package 'php5-fpm' has no installation candidate
E: Package 'php5-mysql' has no installation candidate
E: Package 'php-apc' has no installation candidate

I think they should be replaced by "php-fpm", "php-mysql", and "php-apcu".

[trycoon]

Ok, some more packages missing:
E: Unable to locate package php5-curl
E: Package 'php5-gd' has no installation candidate
E: Unable to locate package php5-intl
E: Package 'php5-imagick' has no installation candidate
E: Unable to locate package php5-imap
E: Package 'php5-mcrypt' has no installation candidate
E: Unable to locate package php5-memcache
E: Unable to locate package php5-ming
E: Unable to locate package php5-ps
E: Unable to locate package php5-pspell
E: Unable to locate package php5-recode
E: Package 'php5-sqlite' has no installation candidate
E: Unable to locate package php5-tidy
E: Unable to locate package php5-xmlrpc
E: Unable to locate package php5-xsl