added unique constraints to all osra_num fields at the db level

- any unanticipated duplicates of osra_num by the software will make the db
  reject input and the app to fail ungracefully
add failing tests
model spec passing
end_date tests green
tests green
restore deleted commit
eye candy
spec/unhappy sponsorship-create path
code review: accept blank dates
show sponsor name
duplicated for almost-obsolete AA.partner#show
Merge pull request #197 from PurityControl/osra-num-db-constraints

added unique constraints to all osra_num fields at the db level
Create rake task for clearing all orphan data from db
Merge pull request #199 from theB264/sponsor_show_correction

show sponsor name
code review:refactor
Merge pull request #174 from theB264/osra208_start_end_dates

Osra208 start end dates
Merge pull request #205 from NikitaAvvakumov/clear_db_rake_task

Create rake task for clearing all orphan data from db
Merge pull request #208 from AgileVentures/develop

Push develop to staging