TEST: added skips to make the tests more readable
PEP 8
Removed prints and del
TEST: Removed all the prints from test_optimize
Merge pull request #482 from Garyfallidis/fix_optimize_defaults_skip

TST: Skip tests for different versions of scipy for optimize.py
RF: deleted unused files
Merge pull request #485 from Garyfallidis/clean_eit

RF: deleted unused files
BF: fix travis version setting

Luckily Steven Silvester noticed that selecting Python versions for the
virtualenvs was not working : https://github.com/nipy/dipy/issues/487
Merge pull request #488 from matthew-brett/fix-travis-again

BF: fix travis version setting
NF: Starting to implement the SFM.
RF: Make sklearn an optional package.
NF: First pass at fitting the thing.
Starting to work on signal prediction.
Abstract out the design matrix construction. Predict.
BF: Make it work with different in/out situations.

On to test that it does something sensible (signal-wise).
TST + BF: More testing, more fixes.
TST: More tests.
Handle errors in the ODF estimation.
When signal is zero, set params to all-zeros, not nans.
TST: update the tests.