Update schema.org examples for 2.0/venkman.
Regenerate schema-warnings.
Added API and contribution information to About page.
Version 2.0.
Release 2.0.

* Linter UI now implemented as an HTML Web Application using AngularJS.
* Linting services now operated using JSON requests, as described in the About section.
* Requests are cached using HTTP caching semantics and Rack::Cache.
* Verfiy SSL is now an option, rather than always being applied.
* Updated schema.org examples for the 1.92 \"Venkman\" release.