919561: replaced reference to zipfile.extractall (aded in python2.6)
919561: fixed variable naming in new extractall method
919561: moved new extractall into a class that extends ZipFile
919561: checking manifest zip for files outside of scope
added tests for cat-manifest
919561: refactored some code into additional methods, fixed naming conventions, and added test cases
919561: moving cat manifest into memory
919561: cleaned up and documented changes
Merge pull request #546 from candlepin/ckozak/rct_extractall

replaced reference to zipfile.extractall (aded in python2.6)