Minor cleanup of title and desc on sqlmap
Slightly better file checks on sqlmap.py
EXITFUNC option should be an OptEnum.
Always replace \ with / for Dexter exploit

Fix for the following:
https://github.com/rapid7/metasploit-framework/commit/48199fec271006ed66c4de639cd39e41f05df511#commitcomment-5419010
Updated the Ultra Minit HTTP bof exploit

After exploiting this application manually I decided to make this
an MSF exploit, only to find that other people had beaten me to it.
However, the existing exploit was broken in a few ways, and this
commit makes those problems go away. They include:

* Correct use of alpha chars in the buffer leading up to the payload
  which results in bad chars being avoided. Bad chars muck with the
  offsets because they get expanded.
* Adjustment of the payload so that it runs in another thread instead
  of in the thread of the request handler. This prevents the session
  from being killed after the hard-coded 60-second timeout that is
  baked into the application.
* The handler thread terminates itself so that the process doesn't
  crash.
* Extra targets were added based on the machines I had access to.
Land #2995 - sqlmap minor cleanup, description & file tests
Apply @jlee-r7's feedback
Land #3027, @OJ's fix for ultraminihttp_bof
Land #3011, @wchen-r7's fix for Dexter exploit
Land #3010 - EXITFUNC as OptEnum
Fix msftidy warning: Suspect capitalization in module title: 'encoder'
Land #3031, @wchen-r7's capitalization fix