Add Simplecov and Coveralls
Add specs for using sprig_file within seed files
Add specs for failure states around custom source/parser definitions
Remove useless rescue/todo

Will add that todo as an issue on the repo
Add specs for delete_existing_by and circular dependency errors
Trim unused method from Sprig::Seed::Factory
Add specs for malformed directives
Remove unused helper method and todo

Will add todo as an issue in the repo
Add spec for using missing attributes in find_existing_by
Add coveralls coverage badge, tidy up some spaces
Remove comments from fixture seed files
Increment version to 0.1.5