travis-ci: Added minimal travis job

Added an additional job to the CI matrix which does a minimal UPM
build (only C, C++, and unit tests) which can run and pass/fail quickly.

Signed-off-by: Noel Eck <noel.eck@intel.com>

docker-compose.yaml

@@ -30,6 +30,12 @@ services:
     extends: base
     image: inteliotdevkit/upm-all
 
+  minimal:
+    extends: base
+    environment:
+      - BUILDFTI=OFF
+    command: bash -c "./scripts/run-cmake.sh && cd build && make && ctest -R unit --output-on-failure"
+
   doc:
     extends: all
     environment: