Updates reset_counters to allow counter name in params

Add support for counter name to be passed as parameter
on `CounterCache::ClassMethods#reset_counters`. This is
to be consistent with the other methods in the module
that all accept counter name.
Document method visibility for designing API docs. [ci skip]

cc https://github.com/rails/rails/issues/14848#issuecomment-41198795
Merge pull request #14428 from jnormore/reset_counters_alias

Updates reset_counters to allow counter name in params
Remove dead test code for unsupported adapters
Merge pull request #15137 from sgrif/sg-remove-dead-code

Remove dead test code for unsupported adapters
Add a type object to Column constructor

Part of #15134. In order to perform typecasting polymorphically, we need
to add another argument to the constructor. The order was chosen to
match the `oid_type` on `PostgreSQLColumn`.