Support for HTTP POST and 'data' / 'form' elements in the post
**Is your feature request related to a problem? Please describe.**
While the documentation for the solution indicates that GET is the default configuration parameter for ObjUrl, it does indeed appear that it is the only option at this time.  I had my ObjUrl configured for POST commands and can confirm that each of the POST (from a network packet capture standpoint) were empty.  I'm not sure if this is a problem with the plugin itself, homebridge, or HomeKit.

**Describe the solution you'd like**
I'd like to be able to use ObjUrl parameters that are both configured for POST and that use the 'data' element of the POST as well as the 'form' element.  I would like to be able to choose which parts of the POST content to use.
