Fine tune watch task

- Add grunt `watch` watch to listen on all the changes inside `spring-xd-ui` and
run the `build`
  - Make sure it works with `livereload` as well
XD-1587 Add module config templates

- Add config templates for
  - rabbitmq source and sink
  - twittersearch, twitterstream sources

Update shared configs

- Use shared configuration for twitter modules
  - update twitterstream, twittersearch modules
- Update for RabbitMQ shared configuration properties

Fix module config keys

- Fix common twitter keys to `twitter.*` and rabbit keys to `rabbit.*`
- Add comments to explain the configuration setup

Update random default values

Remove moduleType specific configuration from modules.yml