Deprecate setting multiple attribute to scalar value
Deprecate setting unique attribute to enumerable value
Added support to `exists?' finder method for a hash of conditions
Fixes #427
Merge pull request #428 from dchandekstark/deprecate-confusing-attribute-behavior

Deprecate confusing attribute setter behaviors
Merge pull request #429 from dchandekstark/427-exists-with-conditions

Added support to `exists?' finder method for a hash of conditions