user object exist, tidy up done

src/main/java/application/DDITApplication.java

src/main/java/command/Command.java

src/main/java/command/CommandComment.java

src/main/java/command/CommandCreate.java

src/main/java/command/CommandDelete.java

src/main/java/command/CommandLs.java

src/main/java/command/CommandNull.java

src/main/java/command/CommandPull.java

src/main/java/command/CommandPush.java

src/main/java/command/CommandSelector.java

src/main/java/command/CommandShow.java

src/main/java/command/CommandTag.java

src/main/java/command/CommandUpdate.java

src/main/java/git/IssueReader.java

src/main/java/git/IssueRepo.java

src/main/java/git/IssueTreeBuilder.java

src/main/java/git/ObjectInserter.java

src/main/java/issueData/Issue.java

src/main/java/issueData/User.java

src/test/java/CommandInitTest.java