rearranged ufunc tests to be more in line with numpy_support.rst

Basically categorized the ufuncs in a similar way that the one used
in NumPy’s documentation
added tests to many NumPy “floating functions”

Also updated the numpy_support file with those functions that worked.
bitwise_not/invert python mode test functional

Also updated the numpy_support.rst file to point that it is working
in python mode
logical_not test fixed. It works in python mode.

Updated numpy_support.rst accordingly
Merge remote-tracking branch 'origin/master' into update-numpy-tests
fixed a couple of typos.
Merge remote-tracking branch 'origin/master' into update-numpy-tests
revised numpy ufunc list, made test use _unimplemented consistently.

All “expected fail” tests dues to a ufunc not yet being supported in
no python mode now use _unimplemented as a decorator.

_unimplemented is just like unittest.expectedFailure, but instead of
catching every exception it just catches TypingErrors (as this is
the error raised for ufuncs that fail to compile in no-python mode).

Revised the list of ufuncs using dir(numpy) as a reference and only
including actual ufuncs.
python 2.6 fix.
fixes issues with divide ufunc

as a bonus, a functional true_divide ufunc in nopython mode.
removed unneeded empty skip_inputs in divide tests.
removed outdated comments.
Merge pull request #559 from numba/update-numpy-tests

Update numpy tests