Add ignore file functionality

[ddzz]

CDVC should support ignoring dependencies through an ignore file, similar to .gitignore.

[raycohen]

a config file that allows you to control all of the CLI flags would be nice. the package.json script line gets really long if you toggle a few things.

also, it would be nice to have some additional features for loosening checks rather than just going all the way to --ignore-dep - things like a max number of different versions allowed in in the repo, specific versions that aren't allowed per dep, etc