Fix bugs identified by trying to use the library
* Refactor MCommGroup.fetch(), mainly to reduce nesting. * Centralize defaulting of list attrs to ; the old code was both overly duplicated and failed to account for some situations. * Most LDAP attributes are not case sensitive, but we were doing a case-sensitive check for the umichGroup object class. * Group display name matching was only casefolding one side of the comparison.