Change default ringbuffer size to 16MB.

This helps performance on segmented stream types and
VOD's where it's common to be able to access data faster
than needed.

By allowing more data to be stored in the ringbuffer we
will have less cache drops in the player when we encounter
spikes in the download speed.
crunchyroll: added an extra check for invalid credentials
crunchyroll: changed instances of e.message for e.args[0] due to incompatibilities with python3
Merge pull request #272 from asermax/crunchyroll-credentials-fix

Added an extra check for invalid credentials
plugins.hitbox: Fix connection provider.
plugins.ilive: Change method of getting the secure token.

Resolves #257.
Update CHANGELOG.rst.
Update AUTHORS.
Release version 1.7.3.
Merge branch 'release/1.7.3' into develop
plugins.ustreamtv: Safer provider validation.
YouTube plugin should accept youtu.be/id URLs

YouTube seems to gradually shift from "youtube.com/watch?v=xxx" URLs to "youtu.be/xxx".
Merge pull request #288 from neithere/patch-1

YouTube plugin should accept youtu.be/id URLs
Add playback of first available video on the page

In case when you only provide a user profile url (e.g. http://www.youtube.com/esgn) this workaround scans for the first "/watch?" link available (if the user if live right now it will be a stream, otherwise a featured video)
Merge pull request #291 from unintended/patch-1

Add playback of first available video on the page
Spelling corrections
cli: Explicitly close the server listening socket.

Avoids a ResourceWarning for “--player-continuous-http” mode.
Prettier JSON cache files