Import py files from old repository which is dead with all week-long history of commits.
Fixed tests - now it is running properly.
Added .travis.yml for Travis CI.
Repair tests for functions, which parse outline nodes in given OPML data.
Wrote test for parse_opml function.
Switched from vulnerable xml.etree to defusedxml, which is more safe. More details in defusedxml page on PyPi.
Wrote descriptive comments for functions.
I was wrote functions which create strings for OPML file from inner representation of categories, RSS feeds names and URLs.
Also, I was wrote the tests for this functions.
But, there is still one little problem, which described at the top of opml_io.py file.
Fixed error, which described in previous commit - switched from default dictionary to OrderedDict.
Also, fixed small mistype in test code.
Added comments for new functions.
Merge branch 'feature/OPML_parser' into develop