Feat/paratest plugin

[bdanchilla]

Contribution Type: new plugin Link to Intent to Implement: https://github.com/Block8/PHPCI/issues/1248

This pull request affects the following areas:

• [ ] Front-End
• [ ] Builder
• [x ] Build Plugins

In raising this pull request, I confirm the following (please check boxes):

• [x ] I have read and understood the contributing guidelines?
• [x ] I have checked that another pull request for this purpose does not exist.
• [x ] I have considered, and confirmed that this submission will be valuable to others.
• [ ] I have created or updated the relevant documentation for this change on the PHPCI Wiki.
• [ ] Do the PHPCI tests pass?

Detailed description of change:

Plugin for paratest https://packagist.org/packages/brianium/paratest. Paratest runs PHPUnit tests in parallel, speeding up build times.

As paratest uses PHPUnit, most of the plugin is the same as the existing php_unit plugin and it extends the PhpUnit class.

A consequence of the parallel processing with paratest is that TAP results are not supported, as with the php_unit plugin. However, JUnit logging is supported and I have added parsing of it after execution to display detailed results.

This is a working first version, but will need some work to make dynamically configurable.

As is, it requires the presence of vendor/bin/paratest, the JUnit log file to be written to junit.log, the phpunit config file to be phpunit-parallel.xml and sets the number of processes to 4

[ptejada]

Your jUnit parser handles skipped and incomplete tests as failures. Ideally there is unittest for this cases.