[haxe] mirror on bitbucket

[Justin L Mills]

I noticed that Github was being attacked again and up/down/slow, so
thought I would open the question on if Haxe should actively mirror
repositories somewhere else like bitbucket? Not specifically suggesting
it should just wondered if it would be a good idea or too much hassle, I
presume with automation it might not be any long term effort just short
term it might require some setup. Perhaps this is not percieved as an
issue but just crossed my mind.