Improved Command Line Interface, Logging, Error Handling and Documentation

This pull-request includes a lot of refactoring.

We are using docopt to parse the command line arguments now.
The logging has been improved... the console logging for a commit of the complete testdata looks like this right now:
```
[ INFO] Configuration repository is "file:///path to python workspace/yadt-config-rpm-maker/repository/config"
[ INFO] Working on revision 1
[ INFO] Found 3 affected hosts
[ INFO] Affected host #0 "berweb01"
[ INFO] Affected host #1 "devweb01"
[ INFO] Affected host #2 "tuvweb01"
[ INFO] Building configuration rpm(s) for host "berweb01"
[ INFO] Building configuration rpm(s) for host "devweb01"
[ INFO] Building configuration rpm(s) for host "tuvweb01"
[ INFO] Uploading 9 rpm(s).
[ INFO] Updating configviewer data.
[ INFO] Elapsed time: 2.56s
[ INFO] Success.
```

Error handling has been improved a bit and documentation for how to develop on CentOS, OpenSUSE and Debian / Ubuntu has been added. Further did I start to document the Configuration parameters.