EST-371: refactoring fixtures in order to reuse in test

Reverted change made recently whereby baseline fixture was called in the person/organisation fixtures; instead make every test run baseline.
Although this is a little bit more boilerplate, it allows test methods (within the same overall test) to be "additive" ... ie run the basic setup(), then add some more fixtures on top for a particular test method (eg create an invoice).

Created composite for creation of different sorts of Leas

In addition:
- BankMandates test was succeeding but a stacktrace shown.  Error due to rename class not reflected in JDOQL.  Refactored to get test to fail, then fixed.
- this also involved breaking out BankAccountAndMandateAbstract so can create just BankAccount, or BankAccount with a BankMandate.
EST-371: completing refactor of fixtures for setting up LeaseItems and terms.
EST-371: more refactoring of existing fixtures.

... en route to writing a fixture to set up an invoice for our lease item term of discount.
EST-371: implemented.

In addition:
- added EstatioFixtureScript, which introduces the notion of fixture scripts being run that do not execute their prereqs.  Useful for being able to run fixture scripts in individual method (over and above the regular setup for that test class)
- use new FixtureScript#runScript convenience method rather than scenarioExecution().install(...).
- added log message when start off tests (so not staring at a blank console wondering what is happening).