Update version number to 3.7.0 (#5793)
Update version number to 3.7.0 (#5793)

* Update version number to 3.7.0

* Add php/releash.sh to Makefile.am

* Make cpp_distcheck exit on fail

protocolbuffers/protobuf-javascript,protocolbuffers/protobuf-javascript,protocolbuffers/protobuf-javascript,protocolbuffers/protobuf-javascript