Support braceless subcolumn syntax (CF.Foo) when fetching column map values

For simple subcolumns without spaces or other special chars, "CF.Foo"
now works.  Previously the simplest accepted syntax was "CF.{Foo}".  The
most complex syntax remains "'__CF.{Foo Bar}__'".
Merge branch '4.0/braceless-subcolumns' into 4.0-trunk

Conflicts:
	lib/RT/Interface/Web.pm