Support for max event size limit

• merged PR #50 thanks to @amandas-sukionis
• libraries update

Possibility to set indefinite retention

Thanks for @joshbernfeld for his PR #48

Community contributions release

• thanks to @mstovicek for making Handler compatible with FingersCrossedHandler
• thanks to @localheinz for a bunch of enhancements and fixes

Hotfix for log event timestamp

Fix issue described here #32 (comment)

Improvement to avoid Rate exceeded errors

Hotfix to avoid AWS API Rate exceeded errors (#33)

* Added throttling mechanism to avoid "Rate exceeded" errors

* Packages updated

* Revert "Packages updated"

This reverts commit a1bb89a88c92c3f20da3ba733e9d93666710c5bf.

* Update package

* Compatibility

* No suggestions on travis build please

* Try to build on 7.2

* PHPUnit updated

* Try another package to analyze code coverage with coveralls

* Removed outdated guzzle/guzzle package from dev dependencies

Minor release with pull merged request

Implement a clone method to register the handler's shutdown function.…

… (#24)

This addresses an issue where a cloned handler does not flush its
buffer.

Typo fix

Merge pull request #21 from maxbanton/hotfix

Fix typo

More accurate timestamp for log records

Merge pull request #20 from maxbanton/issue-13

More accurate timestamp for log records

Empty tags client initialization bugfix

Merge pull request #19 from maxbanton/pulls/16

Fix CloudWatchLogs Client initialization with empty tags

Redefining

Handler was completely rewritten with focus for native support of batch log entries sending.
Some back incompatible changes done.