debug/release: Add minimal debug/release CI builds

This commit enables both a minimal DEBUG and minimal RELEASE build on
Travis-CI.

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

.travis.yml

@@ -16,11 +16,17 @@ jobs:
   include:
     - &run-with-clang-minimal
       stage: Clang 3.8 - minimal with unit tests
-      env: TARGET=minimal
+      env:
+        - TARGET=minimal
+        - CMAKE_BUILD_TYPE=Debug
       before_script: docker-compose pull ${TARGET}
       script:
         - export CC=clang-3.8 CXX=clang++-3.8
-        - BUILDARCH=MOCK docker-compose run ${TARGET}
+        - docker-compose run ${TARGET}
+    - <<: *run-with-clang-minimal
+      env:
+        - TARGET=minimal
+        - CMAKE_BUILD_TYPE=Release
     - &run-with-clang
       stage: Clang 3.8
       env: TARGET=python