Add possible option firefox binary

Possiblity to launch a specific firefox binary
Updated the danish translation
Merge pull request #95 from mandarille/master

Updated the danish translation
Update to Behat 2.5.0
Merge pull request #97 from ludofleury/master

Update to Behat 2.5.0
Merge pull request #94 from bahamut1221/patch-1

Add possible option firefox binary