Labels should be vertically centered

The magic numbers in Bootstrap seem to only work with the specific font
they use. Got rid of some of the hackery. Also change weight to 600
instead of 700, so small labels can be legible in Proxima.
Testing. Apply line-height:normal to FF and IE as well.
Add "appearance" property to search field

Overrides the weird Safari/webkit submit button
Add Tencent Weibo assets

New provider, added to Quilt main in 2.2.9