Bootstrap logic added to wire explorer modules seemelessly

I am using classpath scanning to detect annotations
1. ExplorerGuiceModule - to provide for bindings needed for a pytheas module
2. ExplorerModule - extending AbstractExplorerModule to load module specific properties and layout configs such as menulist, homepage url etc.

Another thing which I have not implemented yet- is to support for disabling explorer modules based on an archaius property (marked as TODO in the code).
HelloWorld app is modified to reflect framework changes.