CHEF-2994 Use mixlib-shellout (r2)


CAVEAT: This change is pending a gem release of mixlib-shellout (with stdin support). Changes in this branch currently points to a git reference

```#run_command -> #shell_out!``` conversions (providers):
  - ```User::UserAdd```
  - ```Subversion```
  - ```Service```, ```Service::InitService```, ```Service::Simple```, ```Service::Systemd```, ```Service::Arch```, ```Service::Debian```, ```Service::Freebsd``` 
  - ```Route```
  - ```Package```, ```Package::Apt```, ```Package::Dpkg```, ```Package::EasyInstall```, ```Package::Freebsd```, ```Package::Macports```, ```Package::Pacman```, ```Package::Rpm```, ```Package::Yum```, ```Package::Zypper```
  - ```Ifconfig```
  - ```Group```, ```Group::Aix```, ```Group::Dscl```, ```Group::Gpasswd```, ```Group::Groupadd```, ```Group::Pw```, ```Group::Suse```, ```Group::Usermod```, ```Group::Window```, 
  - ```Deploy```, ```Deploy::Timestamped```
  - ```Cron```, ```Cron::Solaris```

```#run_command -> #shell_out!``` conversions (others):
  - ```Knife::Ssh```, ```Knife::CookbookSiteShare```
  - ```Chef::Solo```

```#popen4 -> #shell_out!``` conversions (providers):
  - ```User::UserAdd```
  - ```User::Pw```
  - ```Service::Upstart```
  - ```Service::Solaris```
  - ```Service::Debian```
  - ```Package::Zypper```
  - ```Package::Yum```
  - ```Package::Solaris```
  - ```Package::Portage```
  - ```Package::Pacman```
  - ```Package::Macports```
  - ```Package::Dpkg```
  - ```Mount::Mount```
  - ```ErlCall```


Deferred conversions:
  - ```Ifconfig```
  - ```Group::Dscl```
  - ```Cron```
  - ```Cron::Solaris```