[ldapfeed] use LDAP_SCOPES to find user-scope
We already have LDAP_SCOPES dict defining possible scopes, this avoid possible code injection from config...
Thus we can drop global variables already defined in LDAP_SCOPES since they are not used directly anymore.
if repo.system_source.dbdriver == 'postgres':
sql('ALTER TABLE appears ADD COLUMN weight float')
sql('UPDATE appears SET weight=1.0 ')