Merge pull request KnpLabs#195 from KnpLabs/feature/symfony3-compat

Compatibiity with Symfony/Process ~2.3 | ~3.0

Add link to FAQ

Merge pull request KnpLabs#181 from craue/fix-tests-windows

fix tests on Windows

Merge pull request KnpLabs#143 from craue/fix-empty-env-argument

fixed that passing an empty array as env argument would clean default environment variables within the forked process

Merge pull request KnpLabs#143 from craue/fix-empty-env-argument

fixed that passing an empty array as env argument would clean default environment variables within the forked process

Merge pull request KnpLabs#140 from ramunasd/temp_files

Fixed temporary files cleanup

Merge pull request KnpLabs#120 from trsteel88/patch-1

Always return options to default

Merge pull request KnpLabs#129 from piotrantosik/master

Update dev branch alias

Merge pull request KnpLabs#118 from philsturgeon/patch-1

Updated composer install instructions

Merge pull request KnpLabs#117 from nullziu/temporary-file-url-cleanu…

…p-fix

Fixing temporary file unlink when header or footer html is an URL.