Set the puppetrun_cmd's sudo rule to use the puppet_user parameter

This is for when puppet_user is changed to something other than root.  I am unable to make the Augeas[sudo-foreman-proxy] resource work, even as-is in an EL6.5 VM.  I can manually run the "set" commands in augtool just fine.

Here's an example of what works in augtool, but not puppet's Augeas type.

```
augtool> set /files/etc/sudoers/Cmnd_Alias[alias/name = 'FOREMAN_PROXY_COMMANDS']/alias/name "FOREMAN_PROXY_COMMANDS"
augtool> set /files/etc/sudoers/Cmnd_Alias[alias/name = 'FOREMAN_PROXY_COMMANDS']/alias/command[1] "puppet cert *"
augtool> set /files/etc/sudoers/Cmnd_Alias[alias/name = 'FOREMAN_PROXY_COMMANDS']/alias/command[2] "puppet kick *"
augtool> set /files/etc/sudoers/Runas_Alias[alias/name = 'FOREMAN_PROXY_RUNAS']/alias/name "FOREMAN_PROXY_RUNAS"
augtool> set /files/etc/sudoers/Runas_Alias[alias/name = 'FOREMAN_PROXY_RUNAS']/alias/runas_user[1] "root"
augtool> set /files/etc/sudoers/Runas_Alias[alias/name = 'FOREMAN_PROXY_RUNAS']/alias/runas_user[2] "foreman-proxy"
augtool> set /files/etc/sudoers/spec[user = 'foreman-proxy']/user "foreman-proxy"
augtool> set /files/etc/sudoers/spec[user = 'foreman-proxy']/host_group/host "ALL"
augtool> set /files/etc/sudoers/spec[user = 'foreman-proxy']/host_group/command "FOREMAN_PROXY_COMMANDS"
augtool> set /files/etc/sudoers/spec[user = 'foreman-proxy']/host_group/command/runas_user "FOREMAN_PROXY_RUNAS"
augtool> set /files/etc/sudoers/spec[user = 'foreman-proxy']/host_group/command/tag "NOPASSWD"
```
It would leave them if there's more than two, same as before (except that was one).  It could be preceded by an "rm spec[user = '${foreman_proxy::user}']` to wipe out any others.