added itertools.chain.from_iterable to python 2.5
added itertools.chain.from_iterable to python 2.5

jonashaag/jedi,jonashaag/jedi,mfussenegger/jedi,tjwei/jedi,WoLpH/jedi,flurischt/jedi,WoLpH/jedi,tjwei/jedi,dwillmer/jedi,flurischt/jedi,mfussenegger/jedi,dwillmer/jedi