OneJS control generator

Modified `yo onejs` to prompt the user to either generate an app or a control. Also allows for command line arguments, see README for details, or try it yourself :smiley: 

The control option:
* Creates a dir `src/{control_name}`
* 4 files in that dir:
     * {control_name}.html
     * {control_name}.less
     * {control_name}Base.ts
     * {control_name}Model.ts
* A Chai test stub: `test/{control_name}.test.ts`
that would be cool.