Merge pull request #24 from brightmachine/master

Add allowed values and nested variables & a bit of refactoring to make intention clearer
Add space between method name and brace
Update composer.json
Cleaned up travis.yml
Merge pull request #31 from GrahamCampbell/patch-2

Cleaned up travis.yml
Merge pull request #30 from GrahamCampbell/patch-1

Update composer.json
Merge pull request #28 from BlueBayTravel/const-style

Add space between method name and brace
Removed derp
Merge pull request #32 from GrahamCampbell/patch-1

Removed derp
Support comments in .env file
Merge pull request #34 from motin/support-comments-in-env-file

Support comments in .env file
Fix #26 - Required ENV vars should not be empty

 * Also does small formatting cleanup from different merged styles
PHPCS PSR-2 auto fix