Zabbix v2.0.8 SQLi and RCE Module

Conflicts:
	modules/exploits/linux/http/zabbix_sqli.rb

Commit completed version of zabbix_sqli.rb
[FixRM 8482] Fix uninit constant Rex::Exploitation::JavascriptOSDetect

This fixes an uninit constant Rex::Exploitation::JavascriptOSDetect
while using a module with js_os_detect. It was originally reported
by Metasploit user @viniciuskmax

[FixRM 8482]
[FixRM 8489] undefined method `empty?' for nil:NilClass in msfcli

This fixes a undefined method `empty?' for nil:NilClass (NoMethodError)
in msfcli. [SeeRM 8489]
Land #2518, uninitialized JavascriptOSDetect fix
Land #2519, undefined method fix for msfcli
Clean zabbix_sqli
Land #2471, @pyoor's exploit for CVE-2013-5743