[IMPROVEMENT] Ignore production config file

CVSAnalY provides a config.sample file and the possibility to add a
config file argument to run the programm.
If you copy config.sample to config in the same directory, the git
repository is always "unclean".
Solution: Ignore the config while which is used for production.
Merge pull request #21 from andygrunwald/ignore-config

[IMPROVEMENT] Ignore production config file