add _write_connection property to support replicated databases in Model_Crud

Signed-off-by: P. Isaac Hildebrandt <king.isaac@gmail.com>
updated  to reflect current main uri

Signed-off-by: P. Isaac Hildebrandt <king.isaac@gmail.com>
Revert "updated  to reflect current main uri"

This reverts commit 79e05460d343ecf9352da18683ffca4d72771f3b.
added ability to pass 'in' operator to where() in a query builder
tests for query builder 'in' functionality