Adding wunit support
Checking for the wunit driver and adapt the extension to be built up like the one from the MinkExtension
Applied @stof comments for the pull request #8
Remove trailing whitespace
Support redirects with wunit
Remove superfluous mink_driver parameter as requested by @stof
CHG: Make wunit a boolean value
Using canBeUnset() to support the Behat/MinkExtension syntax for activating the wunit driver
Adhere to Symfony2 for activating the wunit mink driver
Auto-detect and auto-activate installed wunit mink driver
Merge branch 'wunit' (PR #8)

The pull request has been rebased before merging it. Closes #8