Add Wordpress XML-RPC Login Scanner

  This module attempts to authenticate against a Wordpress-site (via
  XMLRPC) using username and password combinations indicated by the
  USER_FILE, PASS_FILE, and USERPASS_FILE options.

  The module, checks for XMLRPC response using `demo.sayHello` function
  and sweeps users with `wp.getUsers` function.

  If `verbose` is set `true`, the raw XML response will be printed.

  The module might be usefull when the target's administration page
  is protected.
Added Fixes mentioned by jhart-r7

Details:
* res && res.body fix
  * empty return removed
* vprint added/changed
* is_? convention fixed
* Unknown error removed
* Minor styling issues are fixed
* VERBOSE Option Removed
Empty line fix

Details:
* Empty line fix added to each_user_pass function
Added Fixes mentioned by Firefart

Details:
* string interpolation removed
* Minor styling issues are fixed
  * peer var used
* target_uri added instead of datastore
Added Fixes#2 mentioned by Firefart

Details:
* MSF's HTTP::Wordpress class included and wordpress related
variables are used.
Merge branch 'master' into wordpress-xmlrpc-login-scanner
add wordpress_rpc loginscanner and specs
refactor wordpress_xml_rpc_login

refactor the login module to use the loginscanner class
Merge pull request #1 from dmaloney-r7/wordpress-xmlrpc-login-scanner

Wordpress xmlrpc login scanner
typo fix
Don't need this header
Land #3571 - Add Wordpress XML-RPC Login Scanner (with LoginScanner)