New artwork

• dark top-bar
• moved the search box below the tabs line.
• improved the show host page
• added notifications
• Settings tab now changes title based on the active action
• lots of cleanups - fixes #1066, fixes #926, fixes #628 and many other minor changes...

fixes - #136 - Foreman missing image for Darwin (Mac OS X) hosts

added some status icons, and a bit of DRY