Extend the configuration server by an endpoint for providing version information about the workspace branch

[mariusoe]

In this ticket the configuration server should be extended by an endpoint, that information about the version history of the workspace branch can be retrieved. The live branch doesn*'t have to be considered in this ticket.

It should be possible to retrieve the individual versions (which correspond to the commits in the local repository), including information such as commit ID, author, date, and the files that were modified in them.

The model of the endpoint can be similar to the following:

[
  {
    'name': 'Version 10',
    'id': 'xxxxxxx', # commit id
    'date': 13456789, # timestamp of the commit
    'author': 'admin', # author of the commit
    'changes': [ # modified files
      '/test1.yml',
      '/git/file.yml'
    ]
  },
   {
    'name': 'Version 9',
    'id': 'xxxxxxx', 
    'date': 13456789,
    'author': 'admin',
    'changes': [
      '/test1.yml'
    ]
  },
  ...
]