working py3 port

[mathiasertl]

I have a working Python 3 port of fabric here. Working, as in: all tests work. The code works with Python3.4 and Python2.7 (that's all currently supported python versions, mind you). The diff is not even that great, this includes all changes in the tests as well:

git diff upstream/master --stat
 ...
 29 files changed, 228 insertions(+), 177 deletions(-)

Turns out, you can have a version with the basic functionality working (e.g. run()...) with very few code changes: if you sacrifice Python 2.5 comparability of course.

I'm unsure how I should proceed: If you agree fabric can drop Python 2.5 support, I could start making smaller pull requests right away. If you absolutely need 2.5 support, I could maintain my own fork that py3-people can use.

[bitprophet]

Python 3 support is coming in 2.x, with an alpha due out by end of month. Thanks, but sorry :) (Also, no, dropping 2.5 support in 1.x is not feasible, though we are - as you've found - having to drop it in 2.x, in part due to the 2+3 support headaches.)

[rodrigc]

@mathiasertl: thanks for working on this. Even though @bitprophet is not accepting your patches, please keep your branch open. It is useful for people in a bind who need to use Python 3, and also want to use Fabric