Remove check for defined IN_PHPBB in listener

Fix the comment position
Add Travis base for testing.

Uses: https://github.com/phpbb-extensions/test-framework
Add build status image to README.md
Merge pull request #3 from EXreaction/task/travis

Add Travis base for testing.
Merge pull request #5 from EXreaction/task/build_status_image

Add build status image to README.md
Merge pull request #4 from EXreaction/task/cleanup

Remove check for defined IN_PHPBB in listener