Use alternate DDL statements to avoid error messages

- Attempting to run "CREATE TABLE" each time the app runs will cause error
  messages like:
  ...{f1 = 77; f2 = relation "_default" already exists}...
- Running "CREATE LANGUAGE" each app startup will cause:
  {f1 = 77; f2 = language "plpgsql" already exists}
Merge pull request #163 from twopoint718/master

[fix] Postgres errors on app startup: use alternate DDL statements to avoid