Linker relative path fix for cordova

This might fix this issue:
https://github.com/Zolmeister/grunt-sails-linker/issues/3

Be wary of the `<base>` tag added to the layout.ejs. This should be clearly documented.
Also, haven't actually tested to see if this works or not. I don't particularly like the solution.

The problem being solved is quite difficult, as paths cannot be introspected (without looking at routes config).