Added support of optional full paths for uploads in the trait

This was implemented in the MinkContext in f4b9700 but the trait was not
in sync.
Fixed the regex of the step matching url to avoid breaking formatters

The inner group needs to be non-capturing. Fixes #99
Merge branch '1.3' into 2.0

Conflicts:
	src/Behat/MinkExtension/Context/MinkDictionary.php