Fix deleting nodes defined in a yaml map file.
Fix deleting nodes defined in a yaml map file.

Allow for grains and such to be defined in the map file, without
requiring them. Previously, it was assumed that each node was
defined as a dict, and an exception was thrown if any node was
a mere str. Now, a mix of str's and dict's can be defined in a
node map file.

Example node map:

    base_hp:
      - salt0:
          grains:
            role: frobnitz
      - salt1
      - salt2

saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt