RPG demystification, cont'd

* Major beautification of the help bubbles for attribute bonuses added in commit 2f79472. They now serve as the bullets in the `ul` rather than staggering along the right side.
* Updated help bubble descriptions of attributes for accuracy (though see to-dos, below)
* Added direct Wikia links for all classes displayed in the class selection modal, and turned part of the header into a link to the class system wiki page.
* Updated class descriptions to provide more of an end-user experience perspective.

Still to do / consider:

* The "Stats & Achievements" page is ungainly right now, with a huge left-hand column, not very much in the center, and a wildly variable right side depending on the user's Achievements rap sheet. What do people think about splitting this into a "Character" tab with all the game-mechanics stuff, and an "Achievements" tab with information about the user's accomplishments like pet counts and badges? This would also give us room to put in some truly detailed descriptions of the attributes, which I tried but didn't look good in help-bubble popovers.
* I noticed a `[user.stats.class]` (resulting in "wizard" etc.) in the post-class-selection Justin tour, but injecting the same bit of Angular binding there as used elsewhere threw errors or showed up as raw text, depending on the syntax I used. @lefnire might know better how to fix that?
* I'm not 100% sold on how text-bare the "Choose Your Class" modal is when it first pops up, could be a little disorienting. So I'd be cool with putting some form of the one-liner back in at the top, the unfortunate side-effect being that it gives you ugly scrollbars on the longer class descriptions. Maybe another wordsmith might know how to curtail my verbosity :cat::sweat_drops: