Adds the IDataStoreManager interface.
Updates IMessageHandler and GrandMessageHandler to use IDataStoreManager.
Updates the IDataStore interface with documentation and updates some return types.
Fixes the names of several variables.
Adds InMemoryDataStore and InMemoryDataStoreManager.
Implements InMemoryDataStore.
Fixes naming issue with the data storem anager in GrandMessageHandler.
Adds a space after if.
Fixes more naming issues.
Fixes more naming issues.
Merge pull request #15 from mohammedh123/feature/add-idatastore-manager

Add an IDataStoreManager, fix GrandMessageHandler's AddHandler signature