Add Heartbleed clientside to the release branch

In case Pro has an opportunity to respin for client side coverage.

Note that this is targeted at the release branch, not master, and it's a convenience PR for Rapid7 release engineering if they have a chance to pick it up.

cc @bturner-r7 

This is the module as of 6675464c20dafe5e97f3acd1e41e29424d091471