Fixed bugs in locomotion_bends

Code now runs.  Basically:

1. I had an index off by one, in h__foragingData
2. I was using mean instead of nanmean in h__computeAvgAngles
3. I missed the return statement (easy to do since Matlab doesn't have
them) of h__foragingData
Edited jim_test.py

... amongst other small changes, to slightly improve the test harness.
Fixed numpy Runtime Warnings

numpy throws a warning when you use comparison operations on numpy
arrays containing NaN.  to suppress these I just used a with block and
specified the warnings should be ignored.
Merge remote-tracking branch 'remotes/upstream/master'

Conflicts:
	jim_test.py
	wormpy/WormFeatures.py