Added a raw download servlet at URL http://.../alfresco/dr?contentUrl=...?ticket=...

Added ContentService.getRawReader to get content directly using a content URL.  To access this, you need to be admin.
Fixed EHCacheAdapter to handle non-Serializable values.
Added tests for above and for AbstractRoutingContentStore.


git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/HEAD/root@5841 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261

source/java/org/alfresco/repo/content/ContentStore.java

@@ -71,8 +71,10 @@ public interface ContentStore
      * reader to {@link ContentReader#exists() check for existence}, although
      * that check should also be performed.
      * 
-     * @param contentUrl the path to the content
-     * @return Returns true if the content exists.
+     * @param contentUrl        the path to the content
+     * @return                  Returns true if the content exists, otherwise
+     *                          false if the content doesn't exist or if the URL
+     *                          is not applicable to this store.
      * @throws ContentIOException
      * 
      * @see ContentReader#exists()
@@ -90,6 +92,7 @@ public interface ContentStore
      *
      * @see #exists(String)
      * @see ContentReader#exists()
+     * @see EmptyContentReader
      */
     public ContentReader getReader(String contentUrl) throws ContentIOException;