So long 'ant hsql', hello flyway!

This pull request implements the goals of Issue #2. Now, all one has to do to run Bedework Sometime is:

- Have a quickstart instance installed locally
- Start at a minimum the quickstart's ApacheDS directory
- Clone bw-sometime, then run 'mvn install jetty:run'

The jetty-maven-plugin provided by pull request #4 is updated to provide hsqldb In-Process, using a file URL that is in the target directory. That does mean running the 'clean' goal will wipe away the database. 

The good news with us incorporating Flywaydb is that it will be super easy for us to pre-populate the database with interesting data for all of the users provided in the Bedework Quickstart. This isn't done in this PR, but will be accomplished later.

The SQL scripts for creating the necessary database tables have been removed from sched-assist-spi and are now managed by the new bw-sometime-database artifact.

Getting closer to having something to drop into the Bedework Quickstart!