Make T-Log the main page for the on air section

[pstoica]

you have two options, but I'd consider just changing the On Air link to https://wrektranet2.wrek.org/air/transmitter_log_entries instead of having /air/ point to the T-Log controller.

[pstoica]

• this is the partial for the top navigation bar: https://github.com/wrekatlanta/wrektranet/blob/master/app/views/layouts/_navigation.html.slim
• the welcome page is in a controller called WelcomeController, and the view is here: https://github.com/wrekatlanta/wrektranet/blob/master/app/views/welcome/index.html.slim