Add guardfile

Guardfile

@@ -0,0 +1,19 @@
+# A guardfile for making Danger Plugins
+# For more info see https://github.com/guard/guard#readme
+
+# To run, use `bundle exec guard`.
+
+guard :rspec, cmd: 'bundle exec rspec' do
+  require 'guard/rspec/dsl'
+  dsl = Guard::RSpec::Dsl.new(self)
+
+  # RSpec files
+  rspec = dsl.rspec
+  watch(rspec.spec_helper) { rspec.spec_dir }
+  watch(rspec.spec_support) { rspec.spec_dir }
+  watch(rspec.spec_files)
+
+  # Ruby files
+  ruby = dsl.ruby
+  dsl.watch_spec_files_for(ruby.lib_files)
+end