Add circleci config file

* We can use circleci to test all spec files in solution subdirectories

.circleci/config.yml

@@ -0,0 +1,20 @@
+version: 2.1
+
+orbs:
+  node: circleci/node@5.1.0
+
+jobs:
+  test-solutions:
+    executor: node/default
+    steps: 
+      - checkout
+      - node/install-packages:
+          pkg-manager: npm
+      - run:
+          command: npm run test solution
+          name: Run tests in **/solution/*.spec.js
+
+workflows:
+  test-solutions:
+    jobs:
+      - test-solutions