jedi.process stop raise exceptions on internal errors.

Return object with two attributes. Result and error. If internal
error occurs server will send 500 response code.
Add ert test for completion candidates request.
Fix sending error messages on internal errors.

Don't send None json object together with 500 error code.
Use error message instead.
First not working company location function for emacs.
Fix broken company-jedi-location function.

Normally find object definition at point.
Successful obtain module_path, line pair at point.
Extend company-jedi-point with additional params.

Two new params are current company-prefix and company-arg. Server side
api not implemented yet. Server side ert tests will fail with internal
server error.

Ert tests refactoring. Tests can create buffer context with helper
function.
Extend REST API with current buffer index (point).
Add start_jedi target to Makefile.
Improve logging settings. Write development log on debug.
Start jedi with --debug option on ert tests.
Use custom start_jedi port on make emacs target.

For avoid conflict with installed company-jedi package.
Implement company prefix API.

CompanyJedi constructor extended with following keyword args:
company_prefix, company_arg, point. New keyword used for evaluate
implied content for jedi call. Fix all unittests for new logic.
Add goto-definition function for python mode.

Maybe used when company menu inactivate.