plugins.beattv: Make use of the validation API.
stream.rtmpdump: Fix proxy support.
plugins.ard_mediathek: Refactor to use the validation API.
plugins.filmon_us: Refactor to use the validation API.
Add plugin for connectcast.tv.

Resolves #423.
plugins.ustreamtv: Refactor to use the validation API.
docs: Update theme and use sticky navigation.
cli: Remove leftover unicode_literals import.
travis: Fix only one zip getting uploaded.
docs: Add a player page.