Add the ability to filter which resources to load

[taliaferro]

Right now, the load mechanism pulls in all files in given resource directory. For some use cases this is not enough -- at the moment the easiest way to do a selective import is to move only the dump files you want into a separate directory and load from that.

I'd like to introduce the ability to define a set of glob patterns which would be used to select or reject which dump files to load.
These could be specified in a profile, like:

profiles:
  prod:
    include: prod_*.json
    exclude: pre_*.json

Or at the command line, as in stacker roles load --include '*_admin.json' --exclude 'temp_admin.json'.