add job.disable() and job.enable()

closes #98
Release 0.6.20
Re-add tests for those who use the `npat` option.

Some users have npm run tests automatically after installing. This
PR removes the tests from .npmignore, thus allow them to install
and test happily.

Fixes #106

If accepted, make sure to republish!  Thanks!
Merge pull request #107 from droppedonjapan/master

Re-add tests for those who use the `npat` option.
Release 0.6.21
merge unique in
Release 0.6.22
Remove debugger
Merge pull request #110 from poislagarde/patch-1

Remove debugger
Release 0.6.23
Fix .every() running when using cron strings.

The .every() method wasn't setting the nextRunAt correctly,
defaulting to Date.now() when it was first set up.  After the
initial run the dates would be set correctly.

This fix computes the nextRunAt correctly using
Job.prototype.computeNextRunAt().  I also had to alter that method
a little, scheduling the job to run immediately if supplied a human
interval.

Fixes rschmukler/agenda#100.
Merge pull request #114 from droppedoncaprica/master

Fix .every() running when using cron strings.
Release 0.6.24
document mongo method better.

references [#117] - thanks @cutillo
specify ignore errors in docs
Make mongo options, optional...

There are occasions when the default options for mongo db connection may not be enough - this allows options to be specified in the config file - it should also be 100% backward compatible with current installations.
Remove wrong comma
Merge pull request #118 from davewilliamson/master

Make mongodb options, optional
Update  README.md

Data information are stored under job.attrs
Merge pull request #119 from etiennetatur/patch-1

Update  README.md