28fd0c9c87c6fceb7068776a04c32cd8381fe8f6 removed the path attribute from
execute resource. Even tough this attribute is not being honored by any
provider, some existing cookbooks are still depending on this attribute.

Restore path attribute in execute resource with a deprecation message
that it will be removed in Chef 13.
CHANGELOG update for the issue.
Merge pull request #2571 from opscode/sersut/restore-path

Restore path attribute in execute resource with deprecation warning
knife-windows bootstrap context inherits from Chef::Knife::Core::BootstrapContext
and uses the Chef 11 arity in its constructor (https://github.com/opscode/knife-windows/blob/master/lib/chef/knife/core/windows_bootstrap_context.rb#L36)

In order to protect compatibility with knife-windows make sure that we have a default
for the new parameter that is added to the BootstrapContext constructor.
CHANGELOG info.