Linting of awesometts.services.say module

Brings the `say` command implementation module mostly into compliance
with the coding standards of the pylint checker.
Internal parsing of `say -v ?` output

Removes the add-on's reliance on the sed utility to parse the output of
the call to `say -v ?` and instead does this parsing entirely in Python.
Once confirmed on a Mac OS X installation, issue #17 can be updated.
OS X say improvements for listing voices

Adds sorting and capturing of the voice language for display in the
dropdown.
Merge branch 'bug/say-no-voices' into develop

Brings in fixes to the OS X Say service implementation such that

- parsing is done within Python rather than depending on sed,
- the languages of voices can be displayed in the dropdown, and
- the service is only activated with successful response from say.

Fixes #17 on the pull request list.