PROTON-194: made proton-j the default profile in top level pom. Also Improved JythonTest error reporting

git-svn-id: https://svn.apache.org/repos/asf/qpid/proton/branches/jni-binding@1438467 13f79535-47bb-0310-9956-ffa450edef68
PROTON-192: reduce visibility of constructors to enforce use of factories, thereby abstracting away proton-j vs proton-c-via-JNI.

git-svn-id: https://svn.apache.org/repos/asf/qpid/proton/branches/jni-binding@1438468 13f79535-47bb-0310-9956-ffa450edef68
PROTON-192: added convenience methods to ProtonFactoryLoader so it is useful in both our Java and our Python test code. Updated tests accordingly.

git-svn-id: https://svn.apache.org/repos/asf/qpid/proton/branches/jni-binding@1438469 13f79535-47bb-0310-9956-ffa450edef68