PROTON-249: Use a source file list when compiling java sources to avoid hitting command line length limits

* changed UseJava's add_jar pass a source file list to javac instead of many individual files on the command line
* added function add_jar_from_filelist which behaves like CMake-builtin add_jar but accepts a file contain a list of files
  (used to compile Java output of Swig)
* added ProtonUseJavaSourceFileList to extract a list of Java source files from one or more directories

git-svn-id: https://svn.apache.org/repos/asf/qpid/proton/trunk@1451242 13f79535-47bb-0310-9956-ffa450edef68
PROTON-215: Fix python test error introduced by previous commits.

In interop.py, after decoding a message, Message.body is of <type 'str'> under
plain Python or proton-j Jython, but under proton-jni Jython it is a
<type 'org.apache.qpid.proton.amqp.Binary'>

Check the type and extract the Binary's data as a str if necessary.

git-svn-id: https://svn.apache.org/repos/asf/qpid/proton/trunk@1451329 13f79535-47bb-0310-9956-ffa450edef68