Attach new header panel

The header panel is based on the style Eric is using on the server
pages. I've removed the ModelActionPanel. It will need to be reattached
somewhere. The login boxes also need to be hooked up. I left the
splitter and tab panels unchanged, at least for now.
Bump up font size on tab bars

Easier to read.
Reattach ModelActionPanel

It's now on the Model tab, and instantiated in
Perspective#initializeModel.
Modify styles used in new header panel

I'm trying to match the styles (colors, margins) used elsewhere in the
client.
Apply a new color scheme

I used a color palette adapted from
http://www.colourlovers.com/palette/292482/Terra. Almost every widget
is affected.

DialogBoxes still need to be updated.
Updated DialogBoxes with a custom style
Replace gray font colors with those from palette
Update CSS file

Prune old code, update comments, set color of splitter between Model
and Parameters panels.