Initial CircleCI integration. (apache#4)

Need to start somewhere, so will merge this - am expecting a test failure due to a bug in Parquet at the moment which will be fixed in palantir/parquet-mr#39.

.circleci/config.yml

@@ -0,0 +1,38 @@
+# This file was generated by the excavator check 'excavator/manage-circleci' as specified in .circleci/template.sh.
+# To request a modification to the general template, file an issue on Excavator.
+# To manually manage the CircleCI configuration for this project, remove the .circleci/template.sh file.
+
+version: 2
+jobs:
+  build:
+    docker: [{ image: 'circleci/openjdk:8u171-node' }]
+    resource_class: xlarge
+    environment:
+      GRADLE_OPTS: -Dorg.gradle.console=plain -Dorg.gradle.internal.launcher.welcomeMessageEnabled=false
+      CIRCLE_TEST_REPORTS: /home/circleci/junit
+      CIRCLE_ARTIFACTS: /home/circleci/artifacts
+      _JAVA_OPTIONS: '-Xmx2048m'
+    steps:
+      - checkout
+      - restore_cache: { key: 'gradle-wrapper-{{ checksum "gradle/wrapper/gradle-wrapper.properties" }}' }
+      - restore_cache: { key: 'gradle-cache-{{ checksum "versions.props" }}-{{ checksum "build.gradle" }}' }
+      - run: ./gradlew --no-daemon --parallel --stacktrace  --continue --max-workers=8 --profile check
+      - save_cache:
+          key: 'gradle-wrapper-{{ checksum "gradle/wrapper/gradle-wrapper.properties" }}'
+          paths: [ ~/.gradle/wrapper ]
+      - save_cache:
+          key: 'gradle-cache-v2-{{ checksum "versions.props" }}-{{ checksum "build.gradle" }}'
+          paths: [ ~/.gradle/caches ]
+      - run:
+          command: mkdir -p ~/junit && find . -type f -regex ".*/build/.*TEST.*xml" -exec cp --parents {} ~/junit/ \;
+          when: always
+      - store_test_results: { path: ~/junit }
+      - store_artifacts: { path: ~/artifacts }
+
+workflows:
+  version: 2
+  build:
+    jobs:
+      - build:
+          # CircleCI2 will ignore tags without this. https://circleci.com/docs/2.0/workflows/#git-tag-job-execution
+          filters: { tags: { only: /.*/ } }