FakeResource: Passed a wrong file name.
elpy-rpc-open: Start Python in the root directory.

The old code started Python in the same directory as the first file
being edited, which can cause various problems, from collisions of
libraries used by elpy to problems unmounting those directories.

Thanks to Andrei Zhlobich for the original patch (fixes #64).
test-travis.sh: Set PYTHONPATH to include the package's directory.

The prior behavior relied on the Python interpreter being started from
the installation directory.