add circle-ci config

.circleci/config.yml

@@ -0,0 +1,21 @@
+version: 2
+jobs:
+    build:
+        docker:
+            - image: rust:latest
+        steps:
+            - checkout
+            - restore_cache:
+                key: project-cache
+            - run:
+                name: Stable Build
+                command: |
+                    cargo --version --verbose
+                    cargo build
+            - run:
+                name: Stable Test
+                command: cargo test
+            - save_cache:
+                key: project-cache
+                paths:
+                    - "~/.cargo"