Implement withRequire functionality to append require angular module

Hello Mickel,
First of all thank you for such awesome package. It saved me a lot of time!
At my application we are using RequireJs+Angular, so produced file is not completely valid for us. There are also should be correct header and footer at result angular module. It could be also done by gulp task. However I decided to add one more option to your module. So if withRequire option set to true - produced file would
 be valid RequireJs+Angular module.
Please have a look at my pull request, I'm free to contact and improvements.