This code is in good shape for our next major release so this just
updates the changelog and package version.

Add touch method to HashClient

So that MockMemcacheClient is more complete and can be used for testing
prepend and append cases.

I was reading through the documentation and noticed a minor
inconsistency in the naming of the python-memcached library. This
commit updates the library name to reflect the real library we're
referencing.

For add(), replace(), cas(), and delete(), if noreply is True (or if it
is unset and self.default_noreply is True), the return value is always
True.