Add Dockerfile to make it easier to test changes to vmfloaty by using Docker

Author: mattkirby

.dockerignore

@@ -0,0 +1,12 @@
+**/*.yml
+**/*.yaml
+**/*.md
+**/*example
+**/Dockerfile*
+Gemfile.lock
+Rakefile
+coverage
+spec
+examples
+scripts
+vendor

Dockerfile

@@ -0,0 +1,6 @@
+FROM ruby:2.7
+
+COPY ./ ./
+
+RUN apt-get update && apt-get install -y less
+RUN gem install bundler && bundle install && gem build vmfloaty.gemspec && gem install vmfloaty*.gem