Toggleable footer via config

[marcusmoller]

I've made a few simple commits to allow for a toggleable footer keybinds help bar via the configuration file.

[michael-lazar]

When I run your branch and set show_footer=False, I see a blank screen when I first launch rtv:

[marcusmoller]

That's rather odd, I'm unable to reproduce that bug on new installation. What I did to test:

• clone my repository, install using python setup.py develop and checkout the footer_hide branch
• copy config to home dir using rtv --copy-config
• run rtv in terminal