* Add documentation on how to build android packages
* Check env vars before running build-android.sh
* Add doc strings to build-android.sh
Signed-off-by: Nicolas Oliver <dario.n.oliver@intel.com>
Make a build heriarchy to reduce images size.
Add Android Things builds to build matrix.
Drop gcc-4 builds, use gcc-5 and gcc-6 instead.
Add SonarQube static analysis scans.
Signed-off-by: Nicolas Oliver <dario.n.oliver@intel.com>