Attempt to optimize build

Run unit test and journey test on seperate nodes
Gradle uses --configure-on-demand and --parallel where it wasn't present
Bundle install uses -j4

.travis.yml

 language: java
 jdk:
   - oraclejdk8
+env:
+  - SCRIPT=bin/unit-tests.sh
+  - SCRIPT=bin/journey-test.sh
 
 # http://docs.travis-ci.com/user/migrating-from-legacy
 sudo: false
   - export PATH=$TRAVIS_BUILD_DIR/bin:$PATH  # ensure our tools are prefered over included ones.
 
 script:
-  - bin/unit-tests.sh
-  - bin/journey-test.sh
+  - $SCRIPT
 
 # configure caching (https://docs.travis-ci.com/user/languages/java/#Caching)
 before_cache:

bin/journey-test.sh

   cp -r ${track_root}/exercises tracks/${TRACK}
 
   gem install bundler
-  bundle install
+  bundle install -j4
   gem build trackler.gemspec
 
   # Make *this* the gem that x-api uses when we build x-api.
   pushd $xapi_home
 
   gem install bundler
-  bundle install
+  bundle install -j4
   RACK_ENV=development rackup &
   xapi_pid=$!
   sleep 5
 
     pushd ${exercism_exercises_dir}/${TRACK}/${exercise}
     # Check that tests compile before we strip @Ignore annotations
-    "$EXECPATH"/gradlew compileTestJava
+    "$EXECPATH"/gradlew compileTestJava --configure-on-demand --parallel
     # Ensure we run all the tests (as delivered, all but the first is @Ignore'd)
     for testfile in `find . -name "*Test.${TRACK_SRC_EXT}"`; do
       # Strip @Ignore annotations to ensure we run the tests (as delivered, all but the first is @Ignore'd).
       # The stripping implementations here and in copyTestsFilteringIgnores should be kept consistent.
       sed 's/@Ignore\(\(.*\)\)\{0,1\}//' ${testfile} > "${tempfile}" && mv "${tempfile}" "${testfile}"
     done
-    "$EXECPATH"/gradlew test
+    "$EXECPATH"/gradlew test --configure-on-demand --parallel
     popd
 
     current_exercise_number=$((current_exercise_number + 1))

bin/unit-tests.sh

 pushd exercises
 echo ""
 echo ">>> Running tests..."
-TERM=dumb ../gradlew check compileStarterSourceJava --parallel --continue
+TERM=dumb ../gradlew check compileStarterSourceJava --parallel --configure-on-demand --continue
 popd