- set certs and keys after socket open() as required by offloaded TLSSocket
- Added more checks for invalid handshake test and removed google.com test as
as some modems (e.g. BG96) might contains root CA for google.com
The whole README.md had to be updated to match the internal Confluence documentation, which can now be locked. In the process I also updated any spotted mistakes in tests documentation, removed the obsolete TCPServer tests documentation and added a test which was missing from UDPSocket's main.