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).

Setting includeInGlobalAddressList to false will make these groups not searchable in the sharing UI

Rather than simply retrying after 503 errors, retry after all error
responses since we have also been seeing some spurious 400 responses
from Google.

This causes Lookup groups and their members to be synchronised with
groups in Google. As for people, there are various configuration
options to control which groups to synchronise, what settings should
be applied to them, and to enforce limits on the number of changes the
script will perform.

The group email and display name in Google are based on the Lookup
groupID and groupName, noting that the email is the group's unique
identifier in Google:

email = {groupID}@{groups_domain}
name = {groupName}{group_name_suffix}

where groups_domain is a configurable secondary domain for groups in
Google, and group_name_suffix is a configurable suffix appended to
group names in Google.

Now we have on-boarded users, move away from being compatible with the
authenticator to using displayName in preference to cn/sn.

Closes #5

Closes #4

Add configuration parameters to tweak how we call the Google API. Allow
customisation of API batch size and the delay between calls to the API.
This allows us to work around some Google API rate limits.

Closes #2

Provide an initial implementation f the tool and README documenting how
to install, configure and run it.

Closes #1