Remove null values from contact tables
Check for null values before updating contact info
remove sql script that removes null values.
- this will be included with EVENT-71
Merge pull request #248 from CruGlobal/EVENT-72

Remove null values from contact tables
Merge pull request #247 from CruGlobal/EVENT-71

Migrate people data into contact tables
If registrantType.minimum deposit is null, then the minimum deposit amount should be the full cost
Pretty significant refactoring
 - make sure the same class of objects is passed into `Registration.fromDb()`
 - fix bug in calculations
 - add some comments
 - add registrantTypeId in tests