Find Mailchimp store spenders missing from FreshBooks

**Objective:** Reconcile Mailchimp store customers who have spent at least `{min-spent}` (default 100) with FreshBooks clients, matching on email, and report who appears in only one system.

**Step 1: Get big spenders (mailchimp server)**

Call `mailchimp-get-customer` with `total-spent.min` set to the minimum and `max-records` 200. Keep `email`, name, `total-spent` and `orders-count`. If nothing comes back, report that and stop.

**Step 2: Look each one up in FreshBooks (freshbooks server)**

For each customer call `freshbooks-get-client` with `email` set to the customer's email (and `company` `{company}` if given). For matches call `freshbooks-get-invoice` with `customer-id` set to the client's `id` and total the invoiced amount, by currency.

**Step 3: Report**

Three groups: customers who are also FreshBooks clients (store spend next to invoiced total), customers with no FreshBooks client (possible clients to set up), and a note on any match where the two spend figures differ widely.

**Rules & Guidelines:**

* `mailchimp-get-customer` is on the mailchimp server. `freshbooks-get-client` and `freshbooks-get-invoice` are on the freshbooks server.
* Store spend and invoiced amounts measure different things. Do not call a difference an error, only flag it.
* Read-only. Do not call `freshbooks-add-client` or any add, update or delete tool on either server.

**Validation:**

* Match on email only, case-insensitive. A customer with no email cannot be matched: count them separately.