JSON implementation of Help sections.  Resolves #237
Includes example usage in both server- and client-side code.
Refactored Help class to extend from a base Content class, which acts more like a traditional data model.
No longer returning raw JSON from the Help class, as formatting is a View concern, not a Model concern.
Fix sort order for siblings on Structures.  Resolves #119
Fixed permalinks to subsections with parentheses.  Resolves #243
Since parentheses aren't very URL friendly in the first place, we can remove them safely and this will still work as expected.  Later, we may want to strip and replace all special characters, using a standard slugify function, like Wordpress has.
Merge pull request #259 from krues8dr/master

Fixed #119, #237 and #243 (though I intend to undo the #243 commit as soon as this is merged).