ci(commitlint): configure commitlint

- mention linting for go in README
- configure commitlint with the conventional config
- add Contribution section to readme

progresses #4

.gitignore

@@ -3,4 +3,5 @@ api/api
 api/api.exe
 mongodb/*
 !mongodb/.gitkeep
-client/coverage/
+client/coverage/
+node_modules

.travis.yml

@@ -1,6 +1,10 @@
 dist: xenial
 matrix:
   include:
+    - language: node_js
+      node_js: "node"
+      script:
+        - commitlint-travis
     - language: go
       go: "1.11"
       before_install:

README.md

@@ -37,7 +37,7 @@ Once built the executable can be started with `./api -c=/path/to/config.json`, o
 
 #### Testing
 
-Run `UNPROCESSED_IMAGES=/path/to/image/dir PORT=3333 DATABASE=tagallery DATABASE_HOST=localhost:27017 go test ./...` to test all the packages.
+Run `go tool vet .` to lint the code and `UNPROCESSED_IMAGES=/path/to/image/dir PORT=3333 DATABASE=tagallery DATABASE_HOST=localhost:27017 go test ./...` to test all the packages.
 
 When testing multiple packages at once the config options HAVE to be set via environment variables.  
 A config file in the same directory won't work since `go test` changes the working directory for each test to the directory of the to-be-tested package, and specifying a path via `--config /path/to/config.json` will cause [problems](https://stackoverflow.com/a/49927684) due to the flag not being supported by all packages.
@@ -48,4 +48,13 @@ The client is written using [Vue.js](https://vuejs.org/) with [TypeScript](https
 
 Seek the [Vue Cli ducumentation](https://cli.vuejs.org/guide/cli-service.html) for more information on how to serve, build and test the application via the command line or the Vue Cli UI.
 
-As a quick reference: Start the Vue UI with `vue ui`, or use the scripts `yarn run serve|build|lint|test:e2e|test:unit`.
+As a quick reference: Start the Vue UI with `vue ui`, or use the scripts `yarn run serve|build|lint|test:e2e|test:unit`.
+
+### Contribution
+
+Refer to the [API](#testing) and [Client](#client) section for testing and linting instructions.
+
+Commit messages follow the [Conventional Commits specification](https://www.conventionalcommits.org/) and are enforeced by [Commitlint](https://conventional-changelog.github.io/commitlint/#/) using the [conventional config](https://github.com/conventional-changelog/commitlint/tree/master/%40commitlint/config-conventional#type-enum).  
+Keywords may be added to [close a ticket](https://help.github.com/articles/closing-issues-using-keywords/) or otherwise state the progress, e. g. `progresses #1`.
+
+We are following a [feature branching model](https://guides.github.com/introduction/flow/). Changes to the `master` branch have to be made through PRs and need to pass the [CI pipeline](https://travis-ci.org/), which runs linters and tests, before it can be merged via Github. The PR is automatically squashed before the merge.

commitlint.config.js

@@ -0,0 +1 @@
+module.exports = {extends: ['@commitlint/config-conventional']}

package.json

@@ -0,0 +1,13 @@
+{
+  "devDependencies": {
+    "@commitlint/cli": "^7.5.2",
+    "@commitlint/config-conventional": "^7.5.0",
+    "@commitlint/travis-cli": "^7.5.2",
+    "husky": "^1.3.1"
+  },
+  "husky": {
+    "hooks": {
+      "commit-msg": "commitlint -E HUSKY_GIT_PARAMS"
+    }
+  }
+}