Add editable profile fields to fix bug 1012905

Use Mobile__c instead of MobilePhone field
Created custom field because MobilePhone not accessible via API

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

Fix flake8 errors