Feature/webmock vcr config

@NYULibraries/hydra I had to make configuration changes to how VCR works in order to get it working universally. This may cause you to see changes in the way your cucumber tests run. If there are requests VCR can no longer read we may have to tweak the ignore_requests setting in VCR some more. Please review these changes before I merge them and make any comments below.

- Added `require 'webmock'` to ichabod.rake and moved `WebMock.allow_net_connect!` outside ichabod namespace
- Configured VCR to ignore `__identify__` requests, which are capybara specific and shouldn't be recorded. Read more: https://github.com/vcr/vcr/issues/229. Same for `/hub/session` requests for selenium
- VCR no longer has `:ignore_localhost` because this assumes that every machine that runs the tests will be running jetty, which CI systems will not
- Re-recorded VHS cassettes to not include call to PDS
- Moved calls to PDS to `logged_in_users.yml` cassette and wrapped all tagged `@loggedin` in that cassette. Provides some nice modular cassettes.