Added most of public API to DBManager interface
Altered rest of codebase to reflect those changes
Added test for getting a generic DBManager instance
Renamed LoadFixture to LoadDefaultFixture
Adde LoadPresetFixture method and corresponding unit tests for both
backends
Added a check for existence of file
Added bunch of common testing matches based on gomega
Added unit tests for new matchers
Added few more common matchers.
Renamed Has to Have, it was gramatically incorrect.
Added matchers for testing arbitary SQL statments in chado
Added few unit tests for those functions.
Merge pull request #1 from dictyBase/feature/test-api

Feature/test api