Fix warning in is_function_processor_working.

The path to test_sum.m was wrong. It still works because run_func works
by adding the directory to the path and then calling the function; the
addpath fails with a warning, but test_sum.m is on the path anyway
because it's under matlab/.
Rename matlab functions to match filename.

This fixes some warnings on Octave. (Also update the docs for
pymat_eval, which were still describing web_eval).
Simplify matlabserver.

There's no need for this indirection since we know which function
we're calling.
Merge pull request #83 from isbadawi/misc-cleanup

Fix some warnings in MATLAB code.