Update Caja to r4057 (issue1272042)

[johnfargo]

Reviewers: shindig.remailer_gmail.com, jasvir,

Description:
This patch updates use of Caja to rev 4057.
It updates the calling API as well as its resource-fetching mechanism to
use an injected RequestPipeline.

Using CajaHtmlParser as GadgetHtmlParser, due to its use/support of
namespaces, is required for caja to work as of this CL. Instances using
NekoSimplifiedHtmlParser will *not* work when cajoling content!

This CL does not switch Shindig's default HTML parser to CajaHtmlParser
just yet - a move which is the intended "real" solution - due to a few
small lingering issues with namespaced attributes that are being fixed
by Caja-team shortly.

An enterprising instantiation wishing to support cajoling could
implement a GadgetHtmlParser wrapper to both Neko and Caja, delegating
to the latter only when the gadget is to be cajoled.

Please review this at http://codereview.appspot.com/1272042/show

Affected files:
  java/common/src/main/java/org/apache/shindig/common/PropertiesModule.java
  java/gadgets/pom.xml
   
java/gadgets/src/main/java/org/apache/shindig/gadgets/parse/GadgetHtmlParser.java
   
java/gadgets/src/main/java/org/apache/shindig/gadgets/parse/caja/CajaHtmlParser.java
   
java/gadgets/src/main/java/org/apache/shindig/gadgets/parse/caja/CajaHtmlSerializer.java
   
java/gadgets/src/main/java/org/apache/shindig/gadgets/servlet/CajaContentRewriter.java
   
java/gadgets/src/main/java/org/apache/shindig/gadgets/servlet/RpcServlet.java
   
java/gadgets/src/test/java/org/apache/shindig/gadgets/parse/caja/CajaCssSanitizerTest.java
   
java/gadgets/src/test/java/org/apache/shindig/gadgets/parse/caja/CajaSocialMarkupHtmlParserTest.java
   
java/gadgets/src/test/java/org/apache/shindig/gadgets/parse/caja/old/CajaCssSanitizerTest.java
   
java/gadgets/src/test/java/org/apache/shindig/gadgets/render/SanitizingGadgetRewriterTest.java
   
java/gadgets/src/test/java/org/apache/shindig/gadgets/render/old/SanitizingGadgetRewriterTest.java
   
java/gadgets/src/test/java/org/apache/shindig/gadgets/render/old/SanitizingRequestRewriterTest.java
   
java/gadgets/src/test/java/org/apache/shindig/gadgets/rewrite/RewriterTestBase.java
   
java/gadgets/src/test/java/org/apache/shindig/gadgets/rewrite/old/BaseRewriterTestCase.java
   
java/gadgets/src/test/java/org/apache/shindig/gadgets/rewrite/old/HTMLContentRewriterTest.java
  pom.xml