Testing with predefined buffer sizes for MQTT as well as mbedTLS to
exercise fragmenting outgoing data on both layers. Example test compares
received partition with the actual binary file.
The MQTT broker URL used as default in the examples has ceased operation. All examples and documention have been updated to point to the new domain mqtt.eclipse.org.
This also required an update of the python example test scripts to use TLS 1.2
added docs and tests for mqtt library, small fixes (removed warnings, option for custom outbox, websocket bug fixed for longer transports). refactored to use common tcp_transport component, support for CMake build system.
Closes#2108
