Merge pull request #781 from jubatus/fix-get-model-rpc-error

Improve get_model RPC error handling
Merge pull request #787 from rimms/772

Catch msgpack::type_error in load
Conflicts:

	jubatus/server/framework/save_load.cpp
Add const reference
Merge pull request #765 from jubatus/feature/include_jubatus_type_in_filename

include jubatus-type in filename
Merge pull request #780 from jubatus/fix-mix-log

Fix MIX success log to be printed only when success at least 1 server
Conflicts:

	jubatus/server/framework/mixer/linear_mixer.cpp
Merge pull request #783 from jubatus/fix-interconnection-rpc-error

Improve interconnection RPC error handling