custom payload support
update docs
fix documentation T -> HelloWorldConfiguration
* make getPayloadClass() public
* revert field visibility
add @Notnull on serviceInstanceFactory
Add default implementation of bundle
update documentation
fix class signature documentation
Support easier upgrade

* Rename DiscoveryBundle -> AbstractDiscoveryBundle
* Rename BasicDiscoveryBundle -> DiscoveryBundle
Merge pull request #6 from theo/master

#5 custom payload support