Commit #20

- removed CmdJobCreate
+ added CmdJob

PermissionHandler:
  + added JOB_CREATE
  + added JOB_REMOVE
  + added JOB_REMOVE_OTHERS
  + added MSG_NOPERMISSION
  * changed public static final attribute names to uppercase
MessageSender:
  * changed needed permissions to uppercase names
Job:
  + added leaders
  + added addLeader(String)
  + added removeLeader(String)
  + added isLeader(String)
JobsManager:
  + added addLeader(String, String)
  + added removeLeader(String, String)
  + added isLeader(String, String)