Upgrading rspec so specs can pass again
Add filepicker_image_url to work with policies
Fix typo in application_helper_spec filename
Fix the default policy for filepicker_image_url

* Need read/convert, not pick/store.
* Only call the convert end point when CONVERT_OPTIONS are present.
* Don't mutate @url, just use functions.
Allow filepicker_image_url policy to be overridden

* Rails.application.config.filepicker_rails.policy_proc will be called
  to sign the URL.
* Defaults to read/convert.
Revert "Upgrading rspec so specs can pass again"

This reverts commit b1dd6f581cf6e0f99d5dc4e64c83a243f616bcfa.

Conflicts:

	spec/rails_helper.rb
Remove the policy as proc
Add more spec to cache on filepicker_image_url
Fix rspec version
Passing the default_expiry via configuration
Rename default_expiry to expiry
Add policy docs
Only accepts a callable on Configuration#expiry
Merge pull request #105 from Ink/kitchensurfing-filepicker_image_tag-policy

Image tag policy