travis config: create special branch for coverity checks.

.travis.yml

@@ -36,7 +36,7 @@ addons:
     project:
       name: "assimp/assimp"
       version: 3.2
-      description: "The Asset Importer Lib coverity run"
+      description: "The Asset Importer Lib coverity run, branch coverity_scan"
       notification_email: [email protected]
       build_command_prepend: cmake -G "Unix Makefiles" -DASSIMP_ENABLE_BOOST_WORKAROUND=YES -DASSIMP_NO_EXPORT=$TRAVIS_NO_EXPORT -DBUILD_SHARED_LIBS=$SHARED_BUILD
       build_command: make