Synchronise Lookup institutions.

This causes Lookup institutions and their members to be synchronised with groups in Google, in a similar way to Lookup groups. The unique identifier of the group in Google is it's email address:

email = {instID.lower()}@{insts_domain}

where {insts_domain} is a configurable secondary domain (noting that the local part of the email address is required to be lowercase, whereas all instIDs from Lookup are uppercase).

Closes #7 (closed)

gsuitesync/ldap.py

@@ -130,7 +130,9 @@ class Configuration(ConfigurationDataclassMixin):
         Note that we return GroupEntry instances here since Lookup institutions become groups in
         Google, and this simplifies the sync code by allowing us to handle institutions in the same
         way as groups. The GroupEntry's groupID and groupName fields will be the institution's
-        instID and ou (name) respectively. The description field will not be set.
+        instID and ou (name) respectively. Since Lookup institutions don't have descriptions, we
+        set the description field to the institution's name as well (in Google, the description
+        allows longer strings, and so will not truncate the name).
 
         """
         # This requires 2 LDAP queries. First find the managed institutions.
@@ -142,7 +144,7 @@ class Configuration(ConfigurationDataclassMixin):
         managed_insts = [
             GroupEntry(
                 groupID=_extract(e, 'instID'), groupName=_extract(e, 'ou'),
-                description=None, uids=set(),
+                description=_extract(e, 'ou'), uids=set(),
             )
             for e in self._search(
                 search_base=self.inst_search_base, search_filter=search_filter,