Use git to install developmental version of IPython

Recent changes in IPython requires git submodule for installing
developmental version.
Refactor Makefile; add clean and purge
Ignore travis failures with IPython 0.12.*
Use tornado 2.4.1 when testing against IPython 0.12.*
Use pyzmq 2.2.0.1 when testing against IPython 0.12.*
Record Python package information
Unfreeze tornado
Merge branch 'fix-travis'