Add more flexible way to handle template repository

[montanero]

Is your feature request related to a problem? Please describe.
Currently only default branches of bitbucket-hosted GIT repositories can be used as template repositories. This approach has some problems:

• This is difficult if you are making changes, because you have to make and push them to the default branch, which might cause problems for other users. Workflows with PRs are impossible to maintain
• Some users don't have their repos hosted on bitbucket

Describe the solution you'd like

• Allow to set plain directories as template repository
• Allow to state full git URL to template repository

There might me additional command line options --repository-git-url and --repository-directory and/or appropriate questions when starting it without command line options.
In case of repository-directory no git clone logic would be used, the directory would only be read by ws_ctrl