Port flags from Supermium

[ParkerGit2328]

Port the classic theme flags from Supermium (trapezoid tabs, classic omnibar, etc.)

[krackers]

See #214

basically would have to be done in two parts:

• Get full content view working (no official api on 10.9, so have to hack around with nsthemeframe)
• Change styling of tabs to trapezoid
• Simulate native cocoa toolbar theme (since everything is drawn by chrome, we can't rely on system providing texture)