Merge branch 'release/1.5.1' into develop
Support more advanced filtering for the synonym excludes.

Fixes #159.
Update README.
Add tox.ini.
Merge branch 'docs/mpc-hc' into develop
Merge branch 'hotfix/1.5.2' into develop

Conflicts:
	src/livestreamer/plugin.py
plugin: Add a stream_weight classmethod.

Allows plugins to specify stream weights themself
rathar than relying on the builtin ones.
stream: Use correct type name in __json__.
plugins.ustreamtv: Refactor and add support for UHS.

UHS is UStream.tv's own hybrid RTMP/HTTP streaming protocol.
plugins.azubutv: Fix stream names.
plugins.azubutv: Fix live check.
plugins.azubutv: Fix stream name mismatch.
stream.http: Some small changes.

- Use requets directly rather than urlget
- Let requests prepare the url property
stream.http: Make sure header keys are strings and not bytes.
Add a new exception that all other exceptions inherit from.
plugins.weeb: Remove usage of StreamError.
win32: Add some more comments to livestreamerrc.
cli: Refactor player output and add some new features.

- Add --player-args, allows more control over player command.
- Add --player-http, outputs stream over HTTP
- Add --player-continuous-http, outputs stream over HTTP (forever)
- Add --player-passthrough, passes compatible streams directly
  to the player as a filename.
Add the beginnings of a proper plugin API.

For now it contains a way for plugins to load support
modules that are located in the same plugin directory
as the main plugin.
Split the justintv plugin into multiple parts.

justintv - Justin.tv only code
justintv_common - Code common between Justin.tv and Twitch
twitch - Twitch only code