If a user tries to export and we don't have an email for them, show them this error message

[mikepsinn]

First, change the word "Account" to "Log out" in the Settings page.

Then add this notification when the user presses the export button but we don't have their email:

Hi!  

We'd love to send your measurements, but we don't have your email address. 

To add your email, please:
1. Go to Settings and press Log out
2. Login with Google
3. Try exporting again