Support NTLM authentication for proxies by moving to use 'node-proxying-agent' as the proxy agent

1. Move to use a proxy agent that can authenticate with NTLM proxies. 
  I've created a new proxy agent for http/s requests located at capriza/node-proxying-agent. The agent handles all proxying needs for http requests, including SSL tunneling, Basic authentication and most importantly NTLM authentication.
2. Add input "Directory" for monitoring multiple files in a directory with the ability to include and exclude files