Pulsar managed-ledger interface design

[Arvin Yao <ar...@gmail.com>]

Hello,
	I’m interested in the managed-ledger implementation and has gone into the code. I find that the MetaStore is located in the impl package, but this interface is responsible for managing meta for all managed-ledger, so why not put it in the root package, just as ManagedLedger interface? 
	And for the Entry interface, the method getLedgerId and getEntryId is not necessary and not abstract enough, because we already has the getPosition method.In my opinion, we can remove these two method.
	Thanks all!

Arvin