Update workload parameters

Update ycsbClient.sh

Do not panic! I only added descriptions in the comments' header for each of these classes. Also removed a few unnecessary 'import's.

Fixed bug in initialization, which would make replicas always select replica 0 as the leader, regardless if it was part of the view or not.

Performed refractors on a few variables that are of the type 'CertifiedDecision', so that nomenclature becomes consistent.

Updated parameter 'system.totalordermulticast.nonces' in 'config/system.config'to always make the system create 10 nonces.

After the previous commit, the 'LeaderModule' class became extremely small (just one attribute, one getter and one setter), so I transfered its code and functionality to the 'ExecutionManager' class and deleted 'LeaderModule'. Therefore, it is now the 'ExecutionManager' class that will keep track of the current leader of the SMR protocol.

Changed method 'Op' in interface Recoverable to receive only the content of a requests (instead of an array of TOMMessage objects). Since the MessageContext object now can recreate the original TOMMessage (see commits 18bf9cb1 and 27198df9), it is no longer necessary to deliver the original objects to the Recoverable.

MessageContext no longer stores the full CertifiedDecision. Now it stores only the consensus messages that validates the decision of a consensus instance. This was done to avoid forcing the state transfer log to hold the full propose value, which depending on the requests size, can take too much memory or disk space.

Because of this, the CertifiedDecision is now generated by the replica that asks the state, using information provided by MessaContext objects (see commits 18bf9cb1 and 27198df9) and the functionality provided by BatchBuilder (see commit 2bd2910e) to generate the full propose value that should be included within the CertifiedDecision object.