Several changes to CLI behavior, all minor:
* Inverted the behavior or PgUp/PgDn.  I think it was just wrong
* Added "oldest" and "newest" indicators to the log listing to
  simplify finding your way inside the logs
* Added support for _not_ scrolling when in the middle of the log
  output.  It will now only auto-scroll when already at the front
  of the log so you keep seeing new messages automatically.
* Added a heading for the mic output level
* Limited the mic output level to just the size of the bottom
  area (previously it was proportional to the screen height)
* FIX: Changed the default filter string for viseme
* FIX: The saving of settings was broken
* Ran autopep8 which added a few bits of whitespace here and there

The idiom for handling main() was incorrect to allow the CLI
to be invoked by the mycroft-cli-clent script.

==== Fixed Issues ====