Use importlib instead of __import__
BF: Add backport of importlib for python 2.6
Merge pull request #1 from arokem/stefanv-importlib

ENH: Backport importlib
BF: Relative import
BF: Absolute import instead.
BF: Remove the import that was not in the try clause.
Merge pull request #2 from arokem/stefanv-importlib

BF: Relative import
Merge pull request #471 from stefanv/importlib

Use importlib instead of __import__
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.
NF: Calculate the ODF from the parameters.