* Replace crazy (and soon to be "full") bit fields stored in an account's
securityFlags with a row in a newly created Policy table (thus, fully
expandable)
* Update code from database version 17 to 18; adds Policy table, a
policyKey row in Account, and a revised trigger that deletes Policy
information for deleted Accounts
* Update old PolicySet unit tests to work against the new Policy class
* Add test for the conversion of securityFlags to Policy
* Tested in a variety of scenarios; appears to be functionally equivalent
Change-Id: I1505ee75230d6a0d3c2b62a46326f39c2c7f9eb5
