Add initialization and validation of associations to some models
Model tests belong in test/models
Fix residence controller test
Applicant validates associations
Fix HouseholdMember initialization
Remove unnecessary setting of config.secret_key_base
Applicant validates user presence
Remove merge conflicts from .gitignore
Add pry-nav gem for code stepping
Primitive Salesforce integration

Fixes #16, hooray!

Adds the ability to pull applicants from the Bread for the City Salesforce test
sandbox.  There's a "Pull from salesforce" button on the applicants
page.  If you press it, and the app is was provided with Salesforce
login information in config/databasedotcom.yml and in the environment, it will
sync applicants in the local database with applicants in salesforce.

Right now it only gets first and last names.  Adding more fields is
easy, but tedious, so I'm leaving that for another issue.

I got the login information for the BftC Salesforce test sandbox from Andrew
Lomax (alomax@breadforthecity.org).  If you want to help develop against
that test instance, ask Andrew for login credentials.

The code expects the salesforce password in the environment variable
SALESFORCE_PASSWORD.  That's not tracked in the repo.