Use new AWS account in production for custom and default profile photos

[esparr]

Continues work from big server change-over on Render to get profile photos working in production with Momentum AWS account.

When this work is done:

• a new user gets a new random photo using S3 images upon account creation
• a user’s new uploaded photo is stored in our S3 bucket
• mentor photos stored in S3 show up on the session signup page