Browser-specific display issues

[gmattson92]

There are some display problems that occur when I access the site through Windows:

1. Windows Firefox does not display the Facebook/Google+/Github/LinkedIn circles on the login screen. It shows the "Login!" button, and clicking roughly where the circles should be still allows you to use them correctly. I.e. clicking slightly right of center above the login button selects Github. But the logos are invisible.
   Screenshot: http://i.imgur.com/nFzCRZu.png
2. Windows IE has problems displaying the graph animation. The nodes themselves still move and respond to the mouse, but the arrows connecting them are stationary. This is probably low priority since basically none of our intended user base actually uses IE, and it likely won't be worth the effort to fix.
   Screenshot: http://i.imgur.com/QKq7ZRf.png

[MareoRaft]

We will not support Windows IE but we will support Windows Edge and Windows Firefox.

[MareoRaft]

Also, the login in Firefox is off-center.

Also, the search bar in Firefox has some of the border not showing.

[MareoRaft]

As @mbenos mentioned, the Firefox login is now centered. I'm assuming that that the newer version of FF fixed a CSS issue, but I could be wrong. It seems likely though, since the problem is fixed on all branches I look at (Curriculum, PrefObject, deploy), not just the one Mike was working on (theme2).

Only the search bar issue remains. Some better CSS could fix this problem.