Get back the :type key for mashes in a forward-compatible way

[saverio-kantox]

Relates to #60 and #69.

The issue basically was that the :type method was forcefully removed. Hashie removed :id and :type methods just because they were not part of ruby base anymore, so they were treated as normal key accessors. Removing the method from Mash itself prevented the :type key from being used.

Also, a standard disabling of warning is added to avoid noise for clashing class, first and entries keys:

• https://github.com/intridea/hashie/pull/381 (version 3.5.0) — log attempts to override a built-in method and fails to do so. The accessors were not created anyway.
• https://github.com/intridea/hashie/pull/395 (version 3.5.2) — add the ability to silence those warning in subclasses.

[saverio-kantox]

The corresponding spec fails with current master.

[chriswarren]

Thanks!

[chriswarren]

Published as version 1.0.9