Adding support for exclude option

[cbourdage]

• Added support for an exclude option to be able to explicitly exclude packages from the outdated list of packages.

This is really helpful if you have private repos and the versions can't be identified. For instance the output of something that is uptodate still looks like:

| package-name | 1.0.0 | git | git |

Example usage:

schedule(npmOutdated({ exclude: ['package-name'] }));