Improve README

- Make all URLs links
- Extend the usage howto
- Remove license
Use 'hostname' and 'port' config values

- Fixes example in README, which didn't match actual config
- Using separate config values for hostname and port increases consistency with
  other Mopidy extensions, and it also matches the config of Beets' web plugin
Merge pull request #2 from jodal/rename-config-values

Use 'hostname' and 'port' config values
Merge pull request #1 from jodal/improve-readme

Improve README