distributed solver - not checked thoroughly

Conflicts:
	src/caffe/proto/caffe.proto
distributed server update. bug in synchronous connections.

Conflicts:
	examples/dist_train_server.cpp
	include/caffe/util/io.hpp
	src/caffe/distributed_solver.cpp
	src/caffe/util/io.cpp
	tools/compute_image_mean.cpp
	tools/convert_imageset.cpp
distributed solver: small fix, still bugs
distributed solver still having bugs. Pausing for now...

Conflicts:
	include/caffe/distributed_solver.hpp
	src/caffe/common.cpp
Replace boost.asio with MPI in distributed_solver
Moving distributed training tool