README update for SciPy 2014.
Removed the obsolete planning document.
Updates for PyDy 0.2.0.
Added check_env.py and bumped pydy to 0.2.1.
Minor note on command mode for IPython 2.0+.
Changed to pydy 0.2.1 in check_env.py.
Added note in readme about check_env.py.
Merge pull request #54 from pydy/scipy-2014

Scipy 2014