Dataset existing error should point to location

Then the creation scripts can still ask for information about the
dataset and certificate.
Merge pull request #939 from theodi/feature-include-existing-dataset-url

Include dataset url in duplicate response
Paginate and only load necessary datasets on dashboard
Merge pull request #941 from theodi/hotfix-dashboard-load

Paginate and only load necessary datasets on dashboard
Report published datasets with certificates
Merge pull request #942 from theodi/feature-dashboard-certificate-info

Report published datasets with certificates
Add link to editing questionnaire if authorized
Remove this from campaign page summary as it is too slow
Promote the Mexico questionnaire to beta
Merge pull request #948 from theodi/feature-promote-mexico-to-beta

Promote the Mexico questionnaire to beta
Merge pull request #949 from theodi/feature-campaign-info

Feature campaign info
Show request to claim certificate when not the owner.
Email should definitely be sent async

Otherwise timeouts on the smtp server can bubble up to the user.
Save record to database and use id as parameter for queue

This is less data to serialize and there is now a record of who took the transfer.
Put the owner changing responsibility on the dataset model
Use active support method for non-nil check
In development log email to stdout from jobs worker
Test the actual exploit the code is trying to protect from
Create claim model
Add certificate claim model

I didn’t do this as an extension of transfer as the switching of
logic would’ve lost clarity and there is no reason to limit claims to
a one to one relationship like there is with owner initiated transfers