Remove left over messages.log file
Various cleanup in the storemigration code
Remove unused test that no longer compiled
Final fixes for upgrading 1.9 to 2.1

* Introduces an integrationtests top-level maven module, for tests that span
  across multiple modules and editions.
* Adds support and tests for upgrading stores that already have an
  upgrade_backup directory.
* Aside: rsdr now always shows the hexadecimal representation of records.
  I needed that for some debugging.