Fix generated Persisted classes causing ClassCastException on hot-reload

Avoid causing casting errors due to stale Persisted classes being
cached: detect a classloader change and clear the cache appropriately.
Merge branch '0.3' into pr/29

* 0.3:
  Increment version
  Add Travis build status icon
  Prepare release
  2.10.3 Scala dependency
  Fix Travis GPG signing failure
  Use ThreadLocal for withConnection (#26)
Update multi-connection tests
Refactor to decouple code a bit
Merge branch 'pr/29' into 0.3