feature: avoid copying `bower_components`

When using `--no-bower` as an arguments, it will not copy
the useless `bower_components`.

By default, it will be copied because I didn't want to
override too much the decisions being made by
generator-angular.

Closes #17
feat: add lines to  `.gitignore`

If `.gitignore` is missing some lines, `phonegap:check` will add them.

Closes #3