Corrects HTML rendering, expands RSpec coverage, refactors code slightly.

This commit significantly expands the RSpec coverage. The Deck and Template models now have some rudimentary specs that cover basic functionality. I've refactored the << method in Template to be a little more streamlined, and partitioned the rendering/HTML stuff out of the << logic. It feels a little cleaner, at least.

Perhaps the most important aspect is that it now displays much better -- the 3x3 display is back up and running, using tables. I've got the render_html method re-rendering new tables every 9 cards, which helps the outlines for the cards display on each page. (this might address the "Registration marks" issue?)