Enhancement - Add Layers support to create/update methods

[mwbenowitz]

Currently this doesn't support the newly added layers functionality for lambda functions.

Would be nice to have this as an option in the config.yaml file as an array of layer ARNs, similar to subnet_ids or other options that can accept none or many values.

[Veilkrand]

I will enjoy this enhancement as well. But with the new Lambda Applications for Python (not yet released) everything will change. I don't think layers and dependencies will be handled in the same way.