Custom fields schema

[Maxwell Kanat-Alexander]

	Sean, by the way -- I'm not sure you noticed my comments on the custom
fields bug from looking over your implementation, or if you got my
direct email, but I am fully willing to review your patches, provided
that we break it down into MANY, MANY bugs that incrementally get us
from where we are *now* in Bugzilla to where Custom Fields wants to be.

	In short, the custom fields bug should be a meta-bug.

	-Max