Upgrade Guava to 16.0.1
Add Elasticsearch libraries
Add Jackson libraries
Fix tags preference page font size
Refactor activity preferences keys
Clean up
Add simple JSON data holders
Prepare sample listeners
Setup preferences
Prepare Elasticsearch data store
Add some more string helpers
Implement basic features for Elasticsearch store
Update plug-in definition
Refactor Elasticsearch preferences
Update copyright year
Add extended boolean field editor
Refactor UI preferences