Fix bug with isChangeReviewed()

Bug was introduced where reviews will remain bold on the UI even if
the user has already reviewed the change. This corrects the bug by
fixing the order in which the change messages are sorted in the
isChangeReviewed() method. Additionally, two tests were added to test
this functionality.

Change-Id: I5f946d251de6689a9090af059a01a1616933b07a
Remove duplication of JarEntry comparator

Removed duplication of Comparator<JarEntry> in
the HttpPluginServlet, reducing the copy & paste
of the inner class in the code and improving
readability.

Change-Id: I71201779619435edac9ff70fa1fddd53fa80d373
Removing unnecessary test from ChangeIT and updating test names

There was an unnecessary test in ChangeIT added when bug fixing. I
removed that test as well as renaming the other new test to make its
purpose more clear. Corrected other nits like unnecessary newlines.

Change-Id: Iac54622cbc8fa961535904dab700e1fbbf9af58c