Create Profile and sync_leads: fix bug 1012904

Move choices from UserRegistrationLeadForm to Profile model
Create or update Profile in UserRegistrationLeadForm.save()
Use Rest API and sync updates to salesforce leads
I found it really difficult to figure out what this dict comprehension was doing. I think unrolling this into a loop and adding a comment would be better:

```python
# Create new profile with fields from lead.
profile = Profile(user=user)
for sf_field, profile_field in LEAD_PROFILE.items():
    if sf_field in lead:
        setattr(profile, profile_field, lead[sf_field])
```