Adjust tests to run locally and lint independent of tests

1) Linting failures were reported across the board as emacs 25
failure, 26 failure, and emacs-master failure. Now it will lint once
and show lint failure versus the ominous "build" failure.

2) Switching to this circleci config version you can now run the tests
locally with

```bash
circleci local execute --job [job-name]
```
where job name is one of the four jobs available test-emacs-25,
test-emacs-26, test-emacs-master, and test-lint

.circleci/config.yml

@@ -1,33 +1,51 @@
 version: 2.1
 
 # Default actions to perform on each Emacs version
-default: &default-steps
-  steps:
-    - checkout
-    - run: apt-get update && apt-get install make leiningen=2.8.1-6 -y
-    - run: make elpa
-    - run: emacs --version
-    - run: make test
-    - run: make lint
+commands:
+  setup:
+    steps:
+      - checkout
+      - run: apt-get update && apt-get install make leiningen=2.8.1-6 -y
+      - run: make elpa
+      - run: emacs --version
+  test:
+    steps:
+      - run: make test
+  lint:
+    steps:
+      - run: make lint
 
 jobs:
   test-emacs-25:
     docker:
       - image: silex/emacs:25-dev
         entrypoint: bash
-    <<: *default-steps
+    steps:
+      - setup
+      - test
 
   test-emacs-26:
     docker:
       - image: silex/emacs:26-dev
         entrypoint: bash
-    <<: *default-steps
+    steps:
+      - setup
+      - test
 
   test-emacs-master:
     docker:
       - image: silex/emacs:master-dev
         entrypoint: bash
-    <<: *default-steps
+    steps:
+      - setup
+      - test
+
+  test-lint:
+    docker:
+      - image: silex/emacs:25-dev
+    steps:
+      - setup
+      - lint
 
 workflows:
   version: 2
@@ -36,3 +54,4 @@ workflows:
       - test-emacs-25
       - test-emacs-26
       - test-emacs-master
+      - test-lint