add CircleCI config

.circleci/config.yml

@@ -0,0 +1,36 @@
+version: 2
+jobs:
+  backend sdk:
+    docker:
+      - image: circleci/rust:latest
+    environment:
+      RUST_BACKTRACE: 1
+      RUST_TEST_THREADS: 1
+    steps:
+      - checkout
+      - restore_cache:
+          keys:
+            - backendsdk01-{{ checksum "backend-sdk/Cargo.toml" }}
+      - run: | #TODO: enable 'stable' and 'beta' once `allocator_api` becomes stable
+          cd backend-sdk/
+          rustup toolchain install nightly-2019-09-23
+          rustup default nightly-2019-09-23
+          rustup override set nightly-2019-09-23
+          rustup target add wasm32-unknown-unknown
+          rustup component add rustfmt
+          rustup component add clippy
+          cargo fmt --all -- --check --color always
+          cargo build -v --target wasm32-unknown-unknown --all-features
+          cargo test -v --all-features
+          cargo clippy -v --target wasm32-unknown-unknown
+      - save_cache:
+          paths:
+            - ~/.cargo
+            - ~/.rustup
+          key: backendsdk01-{{ checksum "backend-sdk/Cargo.toml" }}
+
+workflows:
+  version: 2
+  fluence:
+    jobs:
+      - backend sdk