Add *requirement.txt files
Update octal literals to be forward compatible. Prefix is '0o'.
Replace reduce usage

- reduce is no longer a built-in function
update usage of built-in sorted() method

- sorted() no longer accepts cmp argument
- default sorting works for python-bugzilla use case
Do not mutate dict objects when iterating keys
Handle pylint errors related to magic usage
Use bug.__unicode__() instead of built-in unicode method for forward compatibility
Update imports

- some import updates to facilitate easy porting to python3
- remove any usage that is not available in python3, eg:
  urllib2.__version__
Make attachment data handling compatible for python3
Use requests instead of pycurl