* Retoot count increases without reason

-The store_uri method for Statuses was being called on after_create and causing reblogs to be incremented twice.
-This calls it when the transaction is finished by using after_create_commit.
-Fixes #4916.

* Added test case for after_create_commit callback for checking reblog count.

* Rewrote test to keep original, but added one for only the after_create_commit callback.