docs(badges): add experiment, stable, and deprecated badges to API doc.

[ericjim]

Change log

• Add @experimental, @stable, and @deprecated for dgeni to process.
• Add @docsNotRequired as well, not actually being used yet.
• Modify jade.template, which generates a _data.json (a harp.js data context for jade), to include a stability status
• Stylize _hero.jade and _hero.scss to add badges
• Fix an issue where the first line of code examples is overlapped, Change margin to example title style #1104, fix in example-title.scss
• Add inline documentation to make it easy to decipher where the data flows from dgeni to nunjucks to harpjs to jade

Preview

For demonstration purposes, I've included these tags in my local copy of the angular2 project, and hosted a test instance of angular.io. With the current state of angular2 docs, we will only see the doc type, and in some cases (such as FORM_BINDING) the deprecated badge.

• [Experimental] - https://badges-everywhere.firebaseapp.com/docs/ts/latest/api/common/NgFormControl-directive.html
• [Stable] - https://badges-everywhere.firebaseapp.com/docs/ts/latest/api/common/NgSwitch-directive.html
• [Deprecated] - https://badges-everywhere.firebaseapp.com/docs/ts/latest/api/common/FORM_BINDINGS-let.html
• [Undefined] - https://badges-everywhere.firebaseapp.com/docs/ts/latest/api/common/Form-interface.html

The logic which decides which badge to pick is the following:

  // STABILITY STATUS
  // Supported tags:
  // @stable
  // @experimental
  // @deprecated
  // Default is the empty string (no badge)
  var stability = ''; 
  if (_.has(exportDoc, 'stable')) {
    stability = 'stable';
  } else if (_.has(exportDoc, 'experimental')) {
    stability = 'experimental';
  } else if (_.has(exportDoc, 'deprecated')) {
    stability = 'deprecated';
  }

@naomiblack @IgorMinar @petebacondarwin

CLOSES:
#1098
#1097

[naomiblack]

Merged!