applicant email sensitivity

[jesteria]

Applicants may be imported with varying, mixed-case email addresses, such that their resources aren't properly linked.

For example, these two applications likely should have been one: (1475, 1084).

Appy should ensure that applicant emails are inserted lowercased, and that references and applications, etc. are properly linked.

[jesteria]

…Or better yet that applicant.email is a citext (CIEmail) field.

[jesteria]

See: https://github.com/dssg/appy-reviews/compare/applicant-email-ci