fixes #109, adding groups to cloned fields
switching out underscore for lodash
docs & prep for 0.5.0
added bigint type to postgresql
Better error info on schema

Add info to docs about debugging promises
Add early errors to schema interface if table is not defined
Merge branch 'feature/postgres-bigint' of github.com:bryanaka/knex into bryanaka-feature/postgres-bigint

* 'feature/postgres-bigint' of github.com:bryanaka/knex:
  added bigint type to postgresql
updating test output for bigint & bigserial changes
Updating docs for 0.5.0
release 0.5.0