Move optionalDependencies to dependencies.

[fengmk2]

Like source-map is not the optional dependency on Node.js,
should use dependencies instead of optionalDependencies.

[fengmk2]

see npm/npm#2737

optionalDependencies should be optional, event npm install fail, it don't broken the module.

[SomMeri]

@fengmk2 Thank you for taking the time to make the pull request.

Unfortunately, one of AppVeyor tests failed and we can not merge it in when they are failing. The change is failing on node 4.2.1. The other problem is that not all optionalDependencies are non-optional. For example, image-size should not be needed unless you use image-size less.js function.

I would merge in change that moves only really non-optional entries like source-map into mandatory dependencies and does not fail unit tests.

[fengmk2]

@SomMeri Nice!

[matthew-dean]

Is this PR getting updated?

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.