Issue 2119043: Adding an html parser router

[Gagandeep singh]

Reviewers: dev-remai...@shindig.apache.org,

Description:

Adding a GadgetHtmlParserRouter which can route to Caja / Neko parser based on
how its is configured.

This allows us to do stuff like:
  @Override
  public Document parseDomForEncodingDetection(String source) throws
GadgetException {
    for (GadgetHtmlParser parser : ImmutableList.of(nekoParser, cajaParser,
vanillaCajaHtmlParser)) {
      try {
        return parser.parseDom(source);
      } catch (GadgetException e) {
        // Ignore.
      }
    }
    return null;
  }

Please review this at http://codereview.appspot.com/2119043/

Affected files:
 M     java/common/conf/shindig. properties
 M
java/gadgets/src/main/java/org/apache/shindig/gadgets/parse/GadgetHtmlParser.java
 A
java/gadgets/src/main/java/org/apache/shindig/gadgets/parse/GadgetHtmlParserRouter.java
 M
java/gadgets/src/main/java/org/apache/shindig/gadgets/parse/ParseModule.java
 A
java/gadgets/src/test/java/org/apache/shindig/gadgets/parse/GadgetHtmlParserRouterTest.java

Thanks
Gagan