Implement installation of templates with local filepath

[etolstoy]

The user should be able install templates from the local folders. It will look like generamba template install 'MyTemplate' --local ~/Templates/MyTemplate.

After this command Generamba should look for the .gemspec file in the corresponding folder, validate it, modify the Rambafile and move this template to the project folder.

[etolstoy]

After a brief discussion with the team we've decided to move in another direction - specify all the templates in Rambafile and then run generamba template install. The structure would be like this:

project_templates:
- {name: rambler_viper_controller, path: ~/templates/rambler_viper_controller, version: 0.1}
- {name: rambler_viper_view, git: https://github.com/igrekde/rambler_viper_view}
- {name: app_delegate_thinning, version: 1.0}