Store server time values and GUID

[zeroSteiner]

This stores the server start and system times in the client object. This will be necessary for upcoming changes to Metasploit's smb_version module which will consolidate the auxilary/scanner/smb/smb2 module. The smb2 scanner module currently reports the amount of time the remote system has been booted, so to not lose this we'll need it in RubySMB.

For testing you can inspect the object manually, or check out the smb_version WIP. If you choose to go with the later, uptime should be reported for any server that reports both the system and start times.

[coveralls]

Coverage increased (+0.002%) to 97.681% when pulling 2a61d9e on zeroSteiner:feat/times into c329891 on rapid7:master.

[zeroSteiner]

I added another value to store: server_guid which will allow SMB servers that have multiple NICs to be uniquely identified. Changes added in commit f726317.

Output from WIP smb_version:

[*] 192.168.159.31:445    - SMB Detected (versions:1, 2) (preferred dialect:SMB 2.1) (signatures:optional) (uptime:3h 16m) (guid:{6e73395c-f006-4657-a132-b25e96ba2cfb})
[+] 192.168.159.31:445    -   Host is running Windows 7 Professional SP1 (build:7601) (name:WIN-9NSI4A6AIHJ) (workgroup:WORKGROUP)
[*] Scanned 1 of 2 hosts (50% complete)
[*] 192.168.250.100:445   - SMB Detected (versions:1, 2) (preferred dialect:SMB 2.1) (signatures:optional) (uptime:3h 16m) (guid:{6e73395c-f006-4657-a132-b25e96ba2cfb})
[+] 192.168.250.100:445   -   Host is running Windows 7 Professional SP1 (build:7601) (name:WIN-9NSI4A6AIHJ) (workgroup:WORKGROUP)
[*] Scanned 2 of 2 hosts (100% complete)
[*] Auxiliary module execution completed

[zeroSteiner]

Moved to parse_negotiate_response in commit 2a61d9e. Thanks for the review!

[cdelafuente-r7]

I tested with the smb_version WIP module against multiple Windows versions and verified that uptime and server_guid information was reported each time.