added driver_loaded post meterpreter module

Module to loads a KMD using the Windows Service API

Note:
If I try to load an already-loaded driver instead of getting a "error_service_already_running" error I get  a GetLastError = 2 (file not found). Any explanation about this would be welcome. Eg:
```
msf post(driver_loader) > set driver_name MS1_service
driver_name => MS1_service
msf post(driver_loader) > set driver_path system32\\drivers\\msf32.sys
driver_path => system32\drivers\msf32.sys
msf post(driver_loader) > exploit

[*] Service Control Manager opened successfully.
[*] Service object added to the Service Control Manager database.
[+] Driver loaded successfully.
[*] Post module execution completed
msf post(driver_loader) > set driver_name MS2_service
driver_name => MS2_service
msf post(driver_loader) > exploit

[*] Service Control Manager opened successfully.
[*] Service object added to the Service Control Manager database.
[-] There was an error loading the driver. GetLastError=2.
[*] Post module execution completed
```
Some useful commands:

* `driverquery /v | findstr MSF`
* `sc query type= service state= all`
* `sc query MSF`