Revert "Specify full paths to egrep and modprobe"

This reverts commit 0768000f6a26d596f1c15d039034b6de2bb246a3. Turns
out the right solution (that doesn't break the jenkins tests) is to
simply add the path to the module.
Add a path parameter to the execs for egrep and modprobe in load.pp

In its current incarnation, with puppet 3.7, the module fails to perform
the expected tasks with the following error message:

Error: Failed to apply catalog: Parameter unless failed on Exec[modprobe
kvm_intel]: 'egrep -q '^kvm_intel ' /proc/modules' is not qualified and
no path was specified. Please qualify the command or specify a path. at
/opt/puppet-upstream/kmod/manifests/load.pp:28

Error: Failed to apply catalog: Validation of Exec[modprobe kvm_intel]
failed: 'modprobe kvm_intel' is not qualified and no path was specified.
Please qualify the command or specify a path. at
/opt/puppet-upstream/kmod/manifests/load.pp:28

The problem here appears to be the fact that the full paths to both the
modprobe and egrep binaries are not specified. Adding the "path" param
to the exec calls resolves the issue.