CB-7350 Rework createmobilespec

* fix platform flag documentation for --amazon
  - wrap very long lines
  - clarify that /bin/create isn't a system application...
  - drop repetitive: when creating the mobile-spec project
    - it wasn't used consistently...
* support directoryName for --plugman
* delay pushd cli_project_dir until after couldNotFind cordova-plugin-test-framework check
* Brand: BlackBerry