throw away rbenv recipe. now we use librarian and Cheffile
temporary ignore testcase testPostedStringIsJson
cherry picked some commits from retry_socket_opt branch

0e3a70a07abf23af32f9b1a1bc5ae8f205b0b924
6003d6a7511ff6f52531b0338248ca83461ddead
f77b390fba4f218acf3386ab21cde7104f33e177