Add module for eScan command injection
Fix disclosure date
Meterpreter sessions won't get root in this way
Correct check_vars_get to check_request_vars

Since check_vars_get also checked for POSTs.
Reconcile test_old_rubies with the other checks

It is now check_old_rubies.
Add @Firefart's feedback
Land #3236 - Correct check_vars_get to check_request_vars
Land #3237 - Reconcile test_old_rubies with the other checks
Land #3233 - eScan Password Command Injection