Update libraries.html

Added new ruby gem for Web API mail delivery
Merge pull request #266 from markedmondson/patch-1

Update libraries.html
add go library
remove old comment
add ApiExample and Response blocks
convert get method to new ApiExample block
remove leading whitespace
remove request_data block for GET requests
strip whitespace on api response codeblocks
convert all methods to apiexample blocks
convert to apiexample tag
convert to apiexample tag
convert to apiexample tags
convert to apiexample tags
cleanup whitespace
convert to apiexample tags
convert to apiexample tags
convert to apiexample tags
convert to apiexample tags
convert to apiexample tags