Some improvements on launching a feature from an editorpart

Hi,

I changed the launch shortcut labels to be more readable in the menu flow as follows: 
Run as --> Cucumber Feature instead of Run as --> Run Feature and
Debug as --> Cucumber Feature instead of Debug as --> Debug Feature.

Additionally I thought it would be nice to set the file name of a feature as the name for the new launch configurations. 

Also there is only one configuration created for one file instead of a new configuration for each run. 

What do you think?