Realign retab.rb
Make retab.rb smarter about ruby file types

Instead of just relying on a filename of *.rb, use the file utility to
determine file type.

For systems that lack lack 'which' and 'file', fall back to filename
matching.

This is useful for retabbing things like 'msfconsole' that don't have a
.rb extension.
Short circut file checking if it's .rb

Makes things a little faster.
Fix possible port conflict
Add Context to rex sockets plus track them with add_socket
Use payload.encoded because BadChars are defined
Add module for MS13-071
Add minor cleanup
Add comment about the smb_* methods
Adds module for CVE-2013-3568.
Fix whitespace issues.
Use HTTPS in our Gemfile.
Add more refs
Land #2397 - cmd injection in Linksys WRT110 web interface.
Land #2398 - Use https://rubygems.org
Land #2389 - Fix use of Rex sockets from dlink modules
Land #2390 - Use payload.encoded because BadChars are defined
Land #2391 - MS13-071 Microsoft Windows Theme File Handling Vulnerability
Land #2364 - Update retab util