[Feature] CLI

Basic CLI functionality

supports 
    $ pgbuild login
    $ pgbuild logout
    $ pgbuild build <platform>

in support of Cordova 4.0.0, this branch includes the functionality for creating a .pgbuild directory to replace the deprecated .cordova directory. This stores local pgbuild data.

I would like to keep the code review focused on the architecture and functionality of the branch and not issues of style, naming or anything that can be trivially altered.