Merge pull request #1 from gotwalt/master

Added discovery, fixed bug in Speaker class
Update readme and add @gotwalt to gemspec
Move speaker endpoints into module
Add CLI for discovering with Thor
Update readme
Add loudness and prepare 0.2.0
Update readme
Update to do list
Fix album art
Fix typo
Move devices into their own module since we'll eventually have diff types
Use device_description.xml to auto-detect device types during discovery. Really needs parallelization.
Remove freeze and move test data
Join and leave groups
System now owns groups that correctly represent the topology
Code Climate
Fix code smell
Update to do
Update readme
Basic system test