RF: Replacing reconst.odf with reconst.peaks whenever it is necessary
RF: Modified examples to uses reconst.peaks
BF: added peaks.py to git
RF: separated test_odf.py to test_odf.py and test_peaks.py for consistency with the new peaks.py file
Merge pull request #263 from Garyfallidis/fix_pfm_b_matrix

Refactoring peaks calculations to be out of odf.py