Also set an initial user password, and random passwords for all its
resources, on a CreateUser request.

Rename queryConfig to queryTemplate to better reflect its purpose, and
drop all cruft that had to do with config deserialization.

Txn

See merge request !1

Simplifies the code in AccountService a bit, moving more logic into
the request types. The authentication and authorization bits have been
split into a separate authService type for clarity.

Let the server fill in default values for resource and user creation.

By adding a User to the resource validation context, we can implement
more complex checks like verifying that websites have an associated
DAV account, or that the parent resource of a database is actually a
website.

The validationContext contains all configuration and backends that are
relevant to the various validation functions.

Implement a password recovery endpoint, and a way to set the recovery
hints (in the current model, it's a hint/response system).

Verify that we can set and update storage encryption keys correctly.

Start a full HTTP server, backed by an in-memory LDAP server, and test
the API directly.

The new Backend/TX split makes it a bit harder to test the validators,
but do so anyway.

Use a lower level type to abstract LDAP "transactions" (really just
batches of changes) and generate a set of ModifyRequest objects at
commit time. Change the API to let the caller manage the
transaction (TX object) lifetime.

This should make it easier to implement a SQL backend in the future if
necessary, even though LDAP knows no such thing as transactions.

As a result of a better low-level interface, reducing the boilerplate
LDAP code, the business logic in model.go should be quite more
readable.

This is a compiled version of the unboundid-ldap-server project,
with our own patches. All dependencies are included.

This includes a number of validators meant to support the creation of
new users and resources (for instance by checking for resource ID
uniqueness etc).

Also start adding some tests for the AccountService code.