Added jsdoc3 grunt task

**To use:**

1) Add grunt-jsdoc to your site-build node_modules (it's in package.json
for future fresh installs):
npm install grunt-jsdoc --save-dev
2) Build the docs using the 'doc3' grunt task:
grunt doc3

**Notes:**

1) Configured to add jsdoc GFM plugin. Github Flavored Markdown can
be used in doclets.
2) Configured to use template at 'doctemplates/openseadragon', currently
the default jsdoc3 template
3) Configured to put output at 'build/docs3'
jsdoc3 Template Update

Matched colors with OpenSeadragon site, tweaked fonts and sizes.

Left jsdoc defaults commented
Gruntfile Update

Removed jsdoc2-related tasks.
Apache Ant requirement is gone, jsdoc3 runs on node.js.
Removed jsdoc2
Revert "Removed jsdoc2"

This reverts commit e08b62b53c9c3dfa93f03e96d725e23cec80ee00.
Removed jsdoc2
Removed jsdoc2 remnants
Doc template update

Moved the namespace section up in the nav bar
Merged upstream changes
jsdoc Template Update

Added some logging/debugging features for the documentation generation
process. Can be turned on/off in doc-conf.json.
Doc Template Update

Removed GFM plugin. No real benefit from Github Flavored Markdown, and
it added HTML 'p' tags to all descriptions.  Using HTML in doclets like
before works fine.

Removed README.md from index page
Doc Template Update

Renamed jsdoc-default.css to jsdoc-openseadragon.css
Upgraded prettify (source code syntax highlighter, see
http://code.google.com/p/google-code-prettify/)
Doc Template Update

Added redirect pages at old jsdoc2 location (symbols folder).
Doc Template Update

Added group headers for event list in nav bar
Doc Template Update

Added table of contents to top of namespace and class pages
Doc Template Update

Removed code syntax highlighting for now.
Added constructor link to class table-of-contents methods list.
Added some more styling to match main OpenSeadragon site.
Doc Template Update

Quick change to navbar styling. Changed event group titles to gray to
not confuse with main page member titles (which are blue)
Doc Template Update

Added highlight.js to template. Source code can be syntax highlighted as
part of the doc generation process. Nice!

Run 'npm install' in site-build directory to get highlight.js
Doc Template Update

Made a current build of highlight.js a static part of the template.
When an updated version is officially released we can use npm to add it
to our build tools instead.
Removed stray comma