Remove the "path" attribute from "execute" resource which has never been backed by any providers.
Enable guard_interpreters for the execute resource and set the default interpreter for the execute resource to be :execute.

This ensures that attributes of the resource like :environment & :cwd can be inherited by the guard when guard is specified as a string.
Differentiate between the default and the user set guard_attributes in order to be able to warn users correctly when they configure a guard_attribute but use a ruby block in the guard.
Error message update from PR comments.
CHANGELOG update for execute resource guards inheriting parent resource attributes.
Merge pull request #2223 from opscode/sersut/execute-guard-interpreter

Guards of execute resource doesn't inherit command options from its parent resource