Implement methods for the GUI client

[jaRulez]

User Story

• As a Developer,
• I want the implement the methods for the GUI,
• to improve the functionality of the Blockchain.

Acceptance Criteria

• from sequence_number return the message if tempered
• from two sequence_number return the tempered messages in that interval
• Show how many events does the Blockchain hold
• Show how many files does the Blockchain hold
• Show much space the Blockchain occupies

Definition of Done

Feature Code Review has been completed and passed
a) Code is completly implemented
b) Code is structured according to our coding guidelines and commented
c) Code is checked into repository
d) Documentation is updated
Cleanliness of Code
JUnit Tests have been written and passed (if required)
No critical bugs are open
Feature branch has been tagged and merged
Feature Code has been included into the release (candidate)
Product Owners accept Feature