Add editable profile fields to fix bug 1012905

Use UserRegistrationLeadForm in update_profile by adding
ACCOUNTS_PROFILE_FORM_CLASS and AUTH_PROFILE_MODULE settings
UserRegistrationLeadForm now inherits from mezzanine.accounts.forms

Add ACCOUNTS_PROFILE_FORM_EXCLUDE_FIELDS to settings
Exclude salesforce_id, salesforce_sync, and last_salesforce_sync

Add fields to LEAD_PROFILE and remove LEAD_FIELDS
Use Mobile__c instead of MobilePhone field
Created custom field because MobilePhone not accessible via API

Fix flake8 errors
Yes, they are set in salesforce. For the custom fields, we can increase the limits if we need to, but I'm not sure if we can do that for the built-in fields.