adds a unique option to the field options dict so you can set a unique index on one field really easy, although there are now 2 ways to set a unique index on a field, it was getting really annoying to add that separate unique parameter to each schema. Also changes the testing to use PROM_POSTGRES_URL instead of having the values set
adds foreign key support and fixes some bugs I found while testing the foreign keys. Adds install method at the orm level, also adds created and updated properties at the Orm level that wrap _created and _updated. This is to make it match pk wrapping _id