ability to pass down security key into PD initialization
we also added flag for PD to choose whether or not it will run in "installation mode" and allow default security key if it already has a different one set
set of integration tests which test establishment of end-to-end communications (via TCP 6000, hardcoded for now) between PD and ACU sides of the library.
And as a POC one of the tests verifies the behavior of osdp_KeySet command (others were added because I already found a bunch of edge conditions which had to be addressed)
This commit introduces...