Allow other types of content URLs other than store://...

Enforce restriction that all content URLs must be of form protocol://identifier
Allow for read-only stores.
Improved tests so that it is easier, when writing a new store, to determine if the store is compliant or not.


git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/HEAD/root@5899 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261

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

@@ -81,7 +81,7 @@ public abstract class AbstractContentAccessor implements ContentAccessor
     {
         if (contentUrl == null || contentUrl.length() == 0)
         {
-            throw new IllegalArgumentException("contentUrl must be a valid String");
+            throw new IllegalArgumentException("contentUrl is invalid:" + contentUrl);
         }
         this.contentUrl = contentUrl;