Add database interface

[josephmckinsey]

• replaces Begin serialization to SQLite #13

• Updates the existing database entries to better reflect our database design so far

• Exports database tables to SQLite statements

• Adds SQLite database creation logic to Julia

• Adds initial serialization logic to Julia for objects

• Tests database creation and insertion with ACBus.

Caveats:

• OpenAPI objects do not have a public interface on iterating through properties, so we do that
  by converting to JSON-style Dicts. Unfortunately the only way to convert to Dict seems to be passing through strings first.
• We avoid the use of any metaprogramming as much as possible by maintaining lists of column name changes. We should consider changing them on the JSON schema if necessary. An example is from which is a keyword which should be replaced with by from_id in all Arc related objects on the database.