added include/exclude filters

[thibault-ketterer]

Hi,
I added include and exclude filters, hope you find it usefull

[xolox]

Hi and thanks for the pull request! I just merged this and published the result as rotate-backups 1.1. I made significant changes while merging this but I hope you'll agree that they're improvements:

• You used substring matching while I decided to go with shell pattern matching (using Python's fnmatch module) because it allows for prefix, substring and suffix matching using the * wildcard. In general the use of fnmatch pattern elements allows for more flexible include/exclude matching (IMHO).
• I rewrote the inner loops to use Python's any() function and generator expressions because this is nicer to read (IMHO).
• You used -c as the short option for the include list (given that -i was already used for ionice) but I decided to use -I instead. I guess this is just a matter of taste :-).
• I added a test suite earlier today and decided to write tests for the include/exclude logic as well while merging this.

[thibault-ketterer]

yup, these are improvements 👍 (tkdbi was also me, github is messing with my old account since I moved the ssh key from one to another)