FLUID-5516: Updated build site to match new design.

@jobara @acheetham - I've updated the build site to match the new designs. Can you check to make sure I got all the right demos and that the links all go to the right places?
In step 2 of this three-step process, perhaps add the phrase "using 'Import Icons'" (assuming that's the correct method). Also, perhaps add a fourth step,  "click Generate Font," as well as some guidance on what to do with the downloaded archive: Which file is relevant, where in the repo hierarchy to put it, etc.