Move Docker image to new repo, use dev-only image

In #34, development tools were added to the clitest Docker image, making
it both an end user image and a development environment. This was a bad
idea.

This commit separates them in two different images.

- The public clitest image was moved to a new repository:
  https://github.com/aureliojargas/clitest-docker. Now everything is
  automated and releasing a new clitest image to Docker Hub is just a
  matter of adding a git tag to that repository. Everything related to
  that image was removed from this repository.

- The local development image remains here, named `clitest-dev` and
  described in the new `Dockerfile.dev` file. It does not have clitest
  inside it, it's just the development environment. When running the
  image, the current clitest code should be mounted inside it.

In short, everything dev-related is here. After releasing a new clitest
version (here), go to the other repository to make the official Docker
image for it.

Dockerfile.dev

@@ -0,0 +1,19 @@
+# clitest-dev
+# Local Docker image used for clitest development.
+#
+# It has all the required tools for linting and testing clitest code.
+# See Makefile for commands to build and run this image.
+#
+# If you're searching for the official clitest Docker image (for users):
+# https://hub.docker.com/r/aureliojargas/clitest
+
+FROM alpine:3.11
+
+# Perl is required by clitest's --regex matching mode
+RUN apk --no-cache add \
+    bash dash mksh zsh \
+    perl \
+    make \
+    checkbashisms shellcheck
+
+WORKDIR /mnt

Makefile

@@ -1,16 +1,16 @@
 # Developer workflow: run locally the same commands Travis will run in
 # the CI. See the .travis.yml file for the list of commands.
 #
-# By default, the linting and testing targets are run inside the clitest
-# Docker container. To run them directly on the host, avoiding the
-# container, unset the `docker_run` variable. Examples:
+# By default, the linting and testing targets are run inside the
+# clitest-dev Docker container. To run them directly on the host,
+# avoiding the container, unset the `docker_run` variable. Examples:
 #
 #    make test-bash                # test using container's bash
 #    make test-bash docker_run=    # test using host's bash
 
-docker_image = aureliojargas/clitest
-docker_run = docker run --rm -it -v $$PWD:/clitest $(docker_image)
-test_cmd = clitest --first --progress none test.md
+docker_image = clitest-dev
+docker_run = docker run --rm -it -v $$PWD:/mnt $(docker_image)
+test_cmd = ./clitest --first --progress none test.md
 
 default:
 	@echo "Read the comments in the Makefile for help"
@@ -27,7 +27,7 @@ versions:
 	@$(docker_run) sh -c 'apk list 2>/dev/null | cut -d " " -f 1 | sort'
 
 docker-build:
-	docker build -t $(docker_image) .
+	docker build -t $(docker_image) -f Dockerfile.dev .
 
 docker-run:
 	$(docker_run) $(cmd)

README.md

@@ -33,12 +33,19 @@ sudo mv clitest /usr/bin
 
 Now check if everything is fine:
 
-```console
-$ clitest -V
-clitest HEAD
-https://github.com/aureliojargas/clitest/tree/HEAD
-$
 ```
+clitest --help
+```
+
+
+## Docker image
+
+You can also run clitest in a Docker container ([more info in Docker Hub](https://hub.docker.com/r/aureliojargas/clitest)).
+
+```
+docker run --rm -t aureliojargas/clitest --help
+```
+
 
 ## Quick Intro