[Travis] Try sequential test runs

.travis.yml

@@ -15,5 +15,4 @@ before_install:
   - sudo apt-get install -y cmake
   - sudo apt-get install -y libqt4-dev qt4-dev-tools
 
-script: ls -l $QT_PLUGIN_PATH && ls -l $QT_PLUGIN_PATH/sqldrivers && qmake --version && cmake -version
-#script: ctest -VV -S ./CMake/ctkTravisDashboardScript.cmake
+script: ctest -VV -S ./CMake/ctkTravisDashboardScript.cmake

CMake/ctkTravisDashboardScript.cmake

@@ -35,6 +35,7 @@ set(WITH_DOCUMENTATION FALSE)
 set(CTEST_BUILD_CONFIGURATION "Release")
 set(CTEST_TEST_TIMEOUT 500)
 set(CTEST_BUILD_FLAGS "-j4") # Use multiple CPU cores to build
+set(CTEST_PARALLEL_LEVEL 1) # Number of tests running in parallel
 
 # experimental: 
 #     - run_ctest() macro will be called *ONE* time