* Adds 2 new tables and IDL classes. The first is a configuration table
used for defining activity types (config.usr_activity_type). The
second is for tracking activity events. A user activity event is
defined as a combination of user, action (e.g. login), the interface
or 3rd-party responsible for the action (e.g. opac, staffclient,
libraryelf), and the OpenSRF ingress (i.e. the mechanism through which
the action was delivered: e.g. gateway, translator, xmlrpc).
* Includes a front-facing stored procedure (actor.insert_usr_activity),
used for creating new activity entries.
* Adds seed data for some default activity types and reserves the first
1000 IDs for system use.