Vagrantfile: Install recommended recipes.

The VM now matches a fully functional devpi-server.
Gemfile: Upgrade test-kitchen & ChefSpec.

This commit involved rewriting most of the spec tests due to changes in
ChefSpec 3.0.  The helpers that were previously defined in spec/helpers
have been removed or merged into spec/support/matchers.rb.
Merge branch 'feature/upgrade-to-chefspec3' into develop
recipes/server: Make location of pip install configurable.
integration tests: Refactor tests.

The integration test suites are supposed to reflect specific
"real-world" use cases.  I removed the *default* and *runit* suites
since neither was complete.  That leaves us with two suites both
test full-stack deployment using the two service management mechanisms.
So we have one test for *supervisor* and another for *runit*.  The
latter is actually the old *nginx* suite renamed.
recipes/nginx: Start nginx.

The nginx cookbook does not seem to start nginx reliably on all systems.
I had problems with CentOS 6.4 specifically.  The nginx recipe now
starts the daemon as well as creates the log directory.
recipes/client: Install devpi-client package.
metadata: Bump version to 1.1.0.
Merge branch 'feature/add-devpi-client' into develop