Fix race condition

Add locking and duplicate detection

Removed collaborator terminology

fix(repository): remove hard coded host

/cc @michelleN

feat(repo): add chart repo routes to manager

Fix style errors

ref(client): add helper methods to client

fix(gitignore): ignore .DS_Store files

* since it's not being used outside of this package
* also LoadContent -> loadContent for same reason
* This addresses some style issues from #401

* Fixes some style errors in #401

Fix text alignment in dm help output.

chore(examples): add example nginx chart

On OSX, a few things we have (notably, docs) cause OS X to generate
.DS_Store caches. These should not get checked into Git.

* fixes style errors in #401

Add chart configuration

* The explanation of 'manifest' was one tab to far intended.

ref(Makefile): Check for flake8