Fixed issue with gravatar_url for user that no longer exists.
Updated chat styles to be easier to read.

Conflicts:
	app/assets/stylesheets/chat_area/_activity.sass
Updated styles for search input and chat textarea, more polished.
Fixed tab float issue when multiple channel tabs.
Updated chat styles with less padding, more compact and easier to scan.

Conflicts:
	app/assets/stylesheets/chat_area/_activity.sass
Fixed alignment of connect/disconnect messages on small screens.
Align small emoticons to middle of line.
Max height on embedded images with hover to zoom, so images don't take up entire window.
Fixed specificity for connect/disconnect font color.
Merge pull request #350 from alfajango/deleted-user-activities

Fixed issue with gravatar_url for user that no longer exists.
Merge pull request #352 from alfajango/updated-styles

Updated styles
Merge branch 'master' of github.com:kandanapp/kandan
Create ChannelActivities plugin (with empty contents)
Display channel list by simple <li>
Hide action-bar
Apply some styles
Set href property to anchor
Enable to switch channel by clicking channel list
Change channel color when new message has reached
Reset unread channel color when channel is shown