Add exploit for CVE-2014-4872 / domain and SQL creds leakage

This module is an auxiliary for CVE-2014-4872 / CERT VU 121036. BMC Track-It! exposes an unauthenticated .NET remoting service that allows retrieving the domain and SQL database credentials. 
It has been very well tested on all vulnerable versions of Track-It! - version 9 to the latest 11.3.

This is a 0 day exploit as BMC have not responded to CERT and they went ahead with the disclosure. This is a companion module to PR #3965. 

I will add the full disclosure and OSVDB ID's as soon as they become available and the module should be ready to merge.
The credential API has a bug. When entering an alphanumeric value as the address, it throws an error:
```
[-] Auxiliary failed: ActiveRecord::StatementInvalid
PG::InvalidTextRepresentation: ERROR:  invalid input syntax for type
inet: "domain.com"
```
This is even if domain.com is reachable and resolvable. 

We hit the bug on this line because the database_server_name that is returned is an alphanumeric hostname (that MIGHT not be resolvable if it's the Track-It! SQL database is running in a different machine).
I had this set to rhost to try to avoid this bug, but just found out that it also happens with domain names, so we might as well set the real value in the address field and try to fix the bug in Metasploit.

See the last commit for more details.