The Realm was hardcoded to be "aws". It is now a parameter and
can be changed.
Update the hotplug demo to use the realm "awsdemo" and document
how to generate the corresponding key.
TN: eng/toolchain/aws#109
All demos can now be built using a makefile. This will be used to build
demos during nighlty tests. The demos are using the generated makefile.setup
to detect if the proper environment is available.
Update README accordingly.
For JC16-013.