Ignore vendor/bundle

This is the path that vendored rubygems are commonly installed to when
avoiding system- / user-wide installation.

.gitignore

@@ -11,6 +11,7 @@ Gemfile.lock
 gems.locked
 bin/*
 .bundle/*
+vendor/bundle/
 
 # test kitchen
 .kitchen/
@@ -21,3 +22,4 @@ Berksfile.lock
 .zero-knife.rb
 Policyfile.lock.json
 .kitchen.local.yml
+