Separate change log into NEWS; remove comments

Remove everything from dispass.el that is also in README.org and place
the change log list in the NEWS file.
Update README.org

There were some things left unexplained in it.
Change description to show dispass.el is a wrapper

When looking at dispass.el through ELPA it was not clear that
dispass.el is only a wrapper around DisPass and does not actually do
any of the work itself.
Simplify label management functions

By calling `dispass-label' with it's brand spankin' new `--add' and
`--remove' switches the `dispass-add-label' and `dispass-remove-label'
functions can be greatly simplified.  This also removes the need for
the `dispass-file', which assumed the file was in `~/', though that is
not the default case with DisPass anymore.
Change hash(method) to algo(rithm)

To keep terminology in line with the internal workings of DisPass,
hash(method) should be replaced by algo or algorithm, depending on the
situation.
Update NEWS