Adjust width of identity icon

Add a min-width to the identity icon so it is not shrunk at small
window sizes.
Adjust tabstrip and navbar on mac

Add a gradient to the tabstrip and adjust the gradient of the navbar to
match firefox on yosemite
Make tab gradient blend into navbar gradient

Make tab gradient blend into navbar gradient
add min-width to search selector

add min-width so that the icon is not clipped when the window is shrunk
remove gradient

remove the tabstrip gradient on osx
Merge pull request #109 from PalmerAL/master

Adjust width of identity icon, adjust gradients on mac