Feature/circle ci (#2136)

* Try this cache setup
* Need different Docker image
https://stackoverflow.com/questions/53010200/maven-surefire-could-not-find-forkedbooter-class/53085816#53085816
* another attempt to collect surefire results
* Restore cache properly

.circleci/config.yml

@@ -0,0 +1,31 @@
+jobs:
+  build: # runs not using Workflows must have a `build` job as entry point
+    docker: # run the steps with Docker
+      - image: circleci/openjdk:10.0.2-13
+    steps: # a collection of executable commands
+      - checkout # check out source code to working directory
+      - restore_cache: # restore the saved cache after the first run or if `pom.xml` has changed
+          # Read about caching dependencies: https://circleci.com/docs/2.0/caching/
+          key: dockstore-java-{{ checksum "pom.xml" }}
+      - run: mvn clean install # run the actual tests
+      - run: # clean the cache
+          command: |
+            rm -rf ~/.m2/repository/io/dockstore
+            rm -rf ~/.m2/repository/.cache/download-maven-plugin directory
+      - save_cache: # saves the project dependencies
+          paths:
+            - ~/.m2
+          key: dockstore-java-{{ checksum "pom.xml" }}
+      - run:
+          name: Save test results
+          command: |
+            mkdir -p ~/junit/
+            find . -type f -regex ".*/target/surefire-reports/.*xml" -exec cp {} ~/junit/ \;
+          when: always
+      - store_test_results:
+          path: ~/junit
+      - store_artifacts:
+          path: ~/junit
+    branches:
+      ignore:
+        - gh-pages

README.md

@@ -5,6 +5,7 @@
 [![DOI](https://zenodo.org/badge/DOI/10.5281/zenodo.1183288.svg)](https://doi.org/10.5281/zenodo.1183288)
 [![Uptime Robot status](https://img.shields.io/uptimerobot/status/m779655940-a297af07d1cac2d6ad40c491.svg)]()
 [![license](https://img.shields.io/hexpm/l/plug.svg?maxAge=2592000)](LICENSE)
+[![CircleCI](https://circleci.com/gh/ga4gh/dockstore/tree/develop.svg?style=svg)](https://circleci.com/gh/ga4gh/dockstore/tree/develop)
 
 
 # Dockstore