Fix Job & Report class instance variables incorrect documentations.

The problem is any comment that is one-line above attr_reader & attr_accessor
will be considered as their document (via experiment).
So `# class Benchmark::IPS::Job` & `# End of Entry` need to be removed.
Or intentionlly put one more blank line. I think removal these is better.

Currently there is no good way to document attr_accessor as I know of.

On documenting attr_accessor please see:

1) http://stackoverflow.com/questions/7583166/yard-document-custom-getter-setter-pair-like-attr-accessor
2) lsegal/yard#516

So I just use `@attr` for now.

Thanks for the help by @lsegal from lsegal/yard#787.