bugfix in HandleBatchRequest()
Merge pull request #35 from knzm/fix-batchrequest

bugfix in HandleBatchRequest()
Allow multiple calls to the same method in a batch request.

jsonrpc::batchProcedureCall_t is now a std::multimap. Adding
several calls to the same method works as expected.
Merge pull request #36 from j-jorge/master

Allow multiple calls to the same method in a batch request.