Run linter in CI using workflows

We need to separately fix all of the issues that this has identified.

.circleci/config.yml

@@ -1,9 +1,29 @@
 version: 2
+
+workflows:
+  version: 2
+  ci:
+    jobs:
+      - test
+      - lint
+
 jobs:
-  build:
+  test:
     docker:
       - image: circleci/golang:1.10
     working_directory: /go/src/github.com/circleci/circleci-cli
     steps:
       - checkout
       - run: make test
+  lint:
+    docker:
+      - image: circleci/golang:1.10
+    working_directory: /go/src/github.com/circleci/circleci-cli
+    steps:
+      - checkout
+      - run:
+          name: Install
+          command: |
+            go get -u github.com/alecthomas/gometalinter
+            gometalinter --install
+      - run: make lint

Makefile

@@ -28,3 +28,7 @@ test:
 .PHONY: cover
 coverage:
 	go test -coverprofile=coverage.txt -covermode=count ./...
+
+.PHONY: lint
+lint:
+	gometalinter --vendor ./...