Fixing POST, DELETE and PUT to send data via request body.

* Fixing POST, DELETE and PUT to send data via request body.
* Adding debugging for CurbFu and Curl::Easy.
* Fixing/enhancing unit tests.
* Removing `secure_connection` handling, as all connections should be secure.
* Fixing [414 Request-URI Too Large](https://github.com/netdna/netdnarws-ruby/issues/10) from old [netdnarws-ruby](https://github.com/netdna/netdnarws-ruby) client.