[FixRM #4398] Report credentials to database

I'm not able to repro the issue related to mysql_enum stopping when a missed user table, even when access is not granted.

But I'm adding reporting of found credentials, as asked in the same redmine ticket:

*Verification*

- [ ] Just run the module and verify which creds are reported (you need a target mysql awright)

```
msf auxiliary(mysql_enum) > run

[*] Running MySQL Enumerator...
[*] Enumerating Parameters
[*] 	MySQL Version: 5.1.63-0ubuntu0.10.04.1
[*] 	Compiled for the following OS: debian-linux-gnu
[*] 	Architecture: i486
[*] 	Server Hostname: ubuntu
[*] 	Data Directory: /var/lib/mysql/
[*] 	Logging of queries and logins: OFF
[*] 	Old Password Hashing Algorithm OFF
[*] 	Loading of local files: ON
[*] 	Logins with old Pre-4.1 Passwords: OFF
[*] 	Allow Use of symlinks for Database Files: YES
[*] 	Allow Table Merge:
[*] 	SSL Connection: DISABLED
[*] Enumerating Accounts:
[*] 	List of Accounts with Password Hashes:
[*] 		User: root Host: localhost Password Hash: *81F5E21E35407D884A6CD4A731AEBFB6AF209E1B
[*] 		User: root Host: % Password Hash: *81F5E21E35407D884A6CD4A731AEBFB6AF209E1B
[*] 		User: root Host: 127.0.0.1 Password Hash: *81F5E21E35407D884A6CD4A731AEBFB6AF209E1B
[*] 		User: debian-sys-maint Host: localhost Password Hash: *28B9C7ED26AF5402894342B6BB2373699AC7C79B
[*] 		User:  Host: % Password Hash:
[*] 	The following users have GRANT Privilege:
[*] 		User: root Host: localhost
[*] 		User: root Host: %
[*] 		User: root Host: 127.0.0.1
[*] 		User: debian-sys-maint Host: localhost
[*] 	The following users have CREATE USER Privilege:
[*] 		User: root Host: localhost
[*] 		User: root Host: %
[*] 		User: root Host: 127.0.0.1
[*] 		User: debian-sys-maint Host: localhost
[*] 	The following users have RELOAD Privilege:
[*] 		User: root Host: localhost
[*] 		User: root Host: %
[*] 		User: root Host: 127.0.0.1
[*] 		User: debian-sys-maint Host: localhost
[*] 	The following users have SHUTDOWN Privilege:
[*] 		User: root Host: localhost
[*] 		User: root Host: %
[*] 		User: root Host: 127.0.0.1
[*] 		User: debian-sys-maint Host: localhost
[*] 	The following users have SUPER Privilege:
[*] 		User: root Host: localhost
[*] 		User: root Host: %
[*] 		User: root Host: 127.0.0.1
[*] 		User: debian-sys-maint Host: localhost
[*] 	The following users have FILE Privilege:
[*] 		User: root Host: localhost
[*] 		User: root Host: %
[*] 		User: root Host: 127.0.0.1
[*] 		User: debian-sys-maint Host: localhost
[*] 	The following users have PROCESS Privilege:
[*] 		User: root Host: localhost
[*] 		User: root Host: %
[*] 		User: root Host: 127.0.0.1
[*] 		User: debian-sys-maint Host: localhost
[*] 	The following accounts have privileges to the mysql database:
[*] 		User: root Host: localhost
[*] 		User: root Host: %
[*] 		User: root Host: 127.0.0.1
[*] 		User: debian-sys-maint Host: localhost
[*] 	Anonymous Accounts are Present:
[*] 		User:  Host: %
[*] 	The following accounts have empty passwords:
[*] 		User:  Host: %
[*] 	The following accounts are not restricted by source:
[*] 		User:  Host: %
[*] 		User: root Host: %
[*] Auxiliary module execution completed
msf auxiliary(mysql_enum) > creds

Credentials
===========

host             port  user              pass                                       type  active?
----             ----  ----              ----                                       ----  -------
192.168.172.133  3306  root              *81F5E21E35407D884A6CD4A731AEBFB6AF209E1B  hash  true
192.168.172.133  3306  debian-sys-maint  *28B9C7ED26AF5402894342B6BB2373699AC7C79B  hash  true
192.168.172.133  3306                                                               hash  true
```