Make 'dist' path configurable via --target="D:\path"

Grunt will build the files to /dist/ by default, but you can now specify a different target to build to by passing the --target option:

Ex:
grunt --target="D:\MySite"
grunt watch --target="D:\MySite"

* Note that we're now building (to dist or wherever) using the full folder structure (App_Plugins/<name>) which should make deployment a bit easier, especially when we add other folders like /bin/
Simplify conditional
Merge pull request #16 from warrenbuckley/feature/deploy-target

WIP - Make 'dist' path configurable via option