Encoding unicode in "friendly-from" field

[smcmurtry]

Summary | Résumé

This PR changes the way we are encoding the "friendly from" field in the email headers, so that we can include non-ascii characters that show up in service names. The AWS documentation provided examples of how to do this. There are 2 steps:

1. encode the utf-8 characters as base64
2. replace the ascii-encoded "friendly from" field with "MIME encoded-word syntax" that includes the base64 encoded string

Here is a link to the AWS docs that I used.

Test instructions | Instructions pour tester la modification

Reproduce the bug:

1. log into staging
2. visit your service settings page
3. change the name of your service to Accent service èé ÀÂËÎÏÔŒÙÛâçêëîïôœû
4. send an email to yourself
5. observe that the accents are missing from the "friendly from" part of the the email:

Test the fix:

1. Check out this branch and run the api locally
2. connect the locally running admin
3. log in and visit your service page
4. change the name of your service to Accent service èé ÀÂËÎÏÔŒÙÛâçêëîïôœû
5. send an email to yourself
6. observe that the accents are displayed correctly from the "friendly from" part of the the email:

[whabanks]

Tested locally and the accents are present as expected, LGTM!