The registry abstraction is unnecessary and adds direct coupling to the
core types. By using a wrapper, we carry through the default
implementations of the non-mutating operations. The DeleteCollection
method is explicitly patched out since it cannot be correctly
implemented on the storage currently.

As a result, TableConvertor is now exposed.

A few other minor refactorings

* Corrected the case of some variables
* Used functions instead of methods for several helper methods
* Removed the legacy Deleter - service was the only remaining consumer