Remove autoload:ff from build:firefox task, and automate mozilla-addon-sdk installation.

- dreditor.org does not have Firefox, but we want it to build the extension, so autoload needs to be moved elsewhere (later).
- Automating the Mozilla SDK at grunt install time should help in on-boarding new contributors.
Merge pull request #126 from sun/grunt-build-install

Remove autoload:ff from build:firefox task, and automate mozilla-addon-sdk installation.
Updated user project tables collapsing behavior for d.o D7 upgrade.
Fixed "Mark as read" behavior issues two HTTP requests.

Caused by bogus d.o HTML markup.  Selector can be simplified back later.
Updated issue comment form backup for d.o D7 upgrade.
Fixed issue clone feature performs unnecessary request to issue edit form.

Also fixes incomplete form value cloning (missing issue title + parent issue relation).
Merge pull request #131 from sun/form-backup-d7

Updated issue comment form backup for d.o D7 upgrade.
Merge pull request #128 from sun/markasread-duplicate

Fixed "Mark as read" behavior issues two HTTP requests.
Merge pull request #127 from sun/user-projects-collapse

Updated user project tables collapsing behavior for d.o D7 upgrade.
Merge pull request #132 from sun/clone-d7

Fixed issue clone feature performs unnecessary request to issue edit form.
Added new realtime development task watch:ff.

Replaces the former gm + watch:gm tasks to aid in realtime development and debugging.

The new watch:ff task builds a new Firefox extension and autoloads it into Firefox in the most performant way possible.

Note that the stated performance goal is not accomplished yet; the current task averages at 2.8 secs (on Windows).
Clarified enforced exclusion of artifacts in watch files.
Fixed auto-generated documentation in grunt --help.

Requires #133.
Merge pull request #133 from sun/grunt-watch-ff

Added new realtime development task watch:ff.
Merge pull request #134 from sun/grunt-help

Fixed auto-generated documentation in grunt --help.