Proxy and SOCKS support, Windows and Mac OS X support, session variables handling fixes

Fixed

• Basic Windows support
• OS X support
• Improve Stegaref channel referrer templates
• Reset on channel session variables changes

Added

• Python requirements.txt
• Encoding support for sql_console
• Output redirection and inverse grep for file_grep
• Run actions on start depending from the session load
• Proxy and SOCKS support
• Unset session variables
• Show session variables

Modules bruteforce_sql and file_cp, basic system info aliases, and command execution from cli argument

Added

• Module bruteforce_sql
• Additional HTTP headers
• Direct command execution from weevely.py argument
• Whoami, hostname, pwd, uname aliases
• Module file_cp
• CHANGELOG