Keep message/command history for each channel

* Can be navigated with up/down arrow keys
* Currently entered text is preserved when going into history
* When choosing a history entry, previously entered but not submitted text will be restored to input buffer

Closes #75
Remove files no longer needed due to use of Bower
Merge pull request #95 from lorenzhs/history

Keep message/command history for each channel
Merge pull request #96 from lorenzhs/bower

Remove files no longer needed due to use of Bower