some refactorings

- Query build logic removed to appropriate class
- Entities can be instantiated with array of params
- ApiEndpoint handles url building logic
fix empty params
Merge branch 'master' into develop
merge typo fix
make service class singleton
add methods to retrieve people and items from product
finish out unit tests of product
finish unit tests of item
update readme
add missing use statement
item methods related to people now return proper objects
add more tests
merge develop, adopt github flow