Add Windows post module for reading/searching Outlook e-mail

This module allows to read and search e-mails present in Outlook installations. It is using powershell in order to search the e-mails.

When connecting to Outlook using powershell, a security popup appears. WinAPI is used to automatically click on the popup, so access is allowed.

This module is tested on Windows 8.1 x64 with Outlook 2013.
if you do ```keyword.to_s```, you will always get a string and you won't have to check nil?