TEST: adding more tests to catch differen scipy versions
Added more failsafes for old scipy versions
MAINT+TST: update minimum nibabel dependency

Add to travis testing to check in future.
Resolved conflicts
Merge pull request #477 from matthew-brett/update-nibabel-dependency

MAINT+TST: update minimum nibabel dependency
TST: Increase the timeout on the Travis pip install

H/T to @ogrisel for suggesting this:
https://github.com/nipy/dipy/pull/474/files#r20766386
Merge pull request #478 from arokem/travis-time

TST: Increase the timeout on the Travis pip install

H/T to @ogrisel for suggesting this:
https://github.com/nipy/dipy/pull/474/files#r20766386
DOC: changed 0.12+ to >= 0.12
Merge pull request #476 from Garyfallidis/fix_optimize_defaults

Fix optimize defaults for older scipy versions for L-BFGS-B
NF: unique rows of an array.
NF: Added a crutch function. This will need to be removed later on.

And replaced with `move_streamlines`, but I am defering that until I get a
sense of what is happening here.
NF: Added a first-pass implementation of LiFE.
RF: Thinking about simplifying this.

Maybe use dipy.sims.voxel directly?
WIP: Completed the mapping function voxel2fiber, inclduing test.
Matrix allocation more-or-less working.
WIP: Still working out how to create this model.
NF: Added Sparse SGD algorithm for solution of the LiFE equations.
TST + BF: Make sure that input to np.gradient is an array.
RF: Move down the fit function.
RF: docs