NF: added MRtrix and FiberNavigator SH bases
NF: added sh_estimate executable to estimate SH coeffcients with sh_to_sf and sf_to_sh functions in shm.py
added a comment
TEST: wrote tests for sh_to_sf and sf_to_sh functions
DOC: added documentation for the sh_to_sf and sf_to_sh, and corrected the help message in bin/sh_estimate.py
RF - Clean up sf2sh.
STY: Fix typo and PEP8.
addressed all pull requests suggestions
Merge pull request #139 from mdesco/sf2sh

Spherical function to spherical harmonics and back
Created tests for the real_sph_harm family and sf_to_sh in test_shm.py, and have put it in PEP8
RF - have mrtrix/fibernav basis take sh_order as argument and have dipy
use same basis as fibernav
DOC - some documentation fixes
Merge pull request #3 from MrBago/sh_harm_basis

RF - have mrtrix/fibernav basis take sh_order as argument and have dipy
Merge pull request #140 from mdesco/sf2sh_tests

Sf2sh second try at correcting suggestions