Add module to enumerate environment HP via perfd daemon

Module to enumerate the environment HP Operation Manager via perfd daemon.

Application: HP Operations Manager Agent (previously called as HP OpenView Operations Agent)
Homepage: http://h71000.www7.hp.com/openvms/products/openvms_ovo_agent/index.html
Videos: https://www.youtube.com/playlist?list=PL9B29471DF0A14D6E

In Windows, check for opened TCP ports by perfd.exe:
```
opcagt | findstr perfd
perfd (Real Time Metric Access Daemon) (14808) Running
perfdsrv (Real Time Metric Access Service) (7532) Running
```
and then:
``` 
netstat -aon | findstr 14808
TCP 0.0.0.0:5227 0.0.0.0:0 LISTENING 14808
TCP 127.0.0.1:5227 127.0.0.1:64351 ESTABLISHED 14808
```
Usage:
```
msf > use auxiliary/gather/hp_enum_perfd
msf auxiliary(hp_enum_perfd) > show options

Module options (auxiliary/gather/hp_enum_perfd):

   Name     Current Setting  Required  Description
   ----     ---------------  --------  -----------
   CMD      p                yes       Command to execute
   RHOSTS                    yes       The target address range or CIDR identifier
   RPORT    5227             yes       The target port
   THREADS  1                yes       The number of concurrent threads

msf auxiliary(hp_enum_perfd) > set RHOSTS IP
RHOSTS => IP
msf auxiliary(hp_enum_perfd) > run
```
CMD options:
```
msf auxiliary(hp_enum_perfd) > info

       Name: Enum Environment Perfd Daemon
     Module: auxiliary/gather/hp_enum_perfd
    License: Metasploit Framework License (BSD)
       Rank: Normal

Provided by:
  Roberto Soares Espreto <robertoespreto@gmail.com>

Basic options:
  Name     Current Setting  Required  Description
  ----     ---------------  --------  -----------
  CMD      p                yes       Command to execute
  RHOSTS   IP               yes       The target address range or CIDR identifier
  RPORT    5227             yes       The target port
  THREADS  1                yes       The number of concurrent threads

Description:
  Enum Environment Perfd Daemon. Commands: "u" Disks Share, "i" Disk
  space, "p" Process list, "a" Core CPU info, "g" Server status, "l"
  Network Interface (statistics in/out), "T" Scope transactions, "A"
  Others infos, "q" and "Q" => exit.

msf auxiliary(hp_enum_perfd) >
```
Example output:

![p](https://cloud.githubusercontent.com/assets/1926764/4595439/a838bd3c-5099-11e4-9f4e-67793311ee5b.png)

PS: As can be seen above, I changed the path and the filename.

[]'s
"\n#{cmd}\n" is more idiomatic Ruby.