Fixed entity-fields issue

- Entity-fields simplified to only accept fields for that particular entity.
  This removes the ability to specify related table fields by default, which
  I'd consider more reasonable behavior.
- Fields are added during select* if they exist in the entity map. Otherwise, all (*).

Fixed failing tests and added specific entity-fields test

Tests utilizing entity-fields were passing previously because entity-fields
was not working (i.e. not providing default fields for SELECT).  Many tests
failed after applying the bug fix because they expected * (all) fields.
So, 'entity-fields' was removed from entities that were not explicitly
testing that functionality and a new simple select case was added.

Updated select* docstring to reflect new behavior.
Merge pull request #190 from derfcat/master

Fixed entity-fields issue #157