(FACT-570) Update ffi, win32-security, win32-dir

 - Upgrade FFI gem to 1.9.3 from 1.9.0
 - Upgrade win32-security gem to 0.2.5 from 0.1.4
 - Upgrade win32-dir gem to 0.4.8 from 0.4.3
(FACT-570) Remove win32-dir patch

The win32-dir patch was merged upstream in version 0.4.4[1] and
is still present in 0.4.8, and can be removed.

[1] https://github.com/djberg96/win32-dir/commit/f6ed8a72b17a082bea966b0a8f51375d91c7a2b5
(FACT-570) Remove win32-security authenticated users patch

Previously, we were patching win32-security version 0.1.4, because
it called strip on a binary string sid. As a result, the gem would
truncate SIDs ending with whitespace characters, e.g. 'Authenticated
Users' is 'S-1-5-11', and ASCII character 11 is a vertical tab.

Our patch was merged upstream in version 0.2.3[1] and works
correctly in 0.2.5:

    $ cmd /c gem list win32-security
    win32-security (0.2.5)
    $ ruby.exe -r win32/security -e "puts Win32::Security::SID.new('Authenticated Users')"
    S-1-5-11

https://github.com/djberg96/win32-security/commit/e197c389957d11397b5ffce024ee98924b838d7e
Merge branch 'ticket/master/FACT-570-update-gems' into 1.9.3

* ticket/master/FACT-570-update-gems:
  (FACT-570) Remove win32-security authenticated users patch
  (FACT-570) Remove win32-dir patch
  (FACT-570) Update ffi, win32-security, win32-dir
(PUP-2389) Add ruby 2.0.0-x64

 - This provides a vendored ruby 2.0.0-p481 based currently on the
    ruby installer for Windows.
 - Removes Tcl/Tk as they are not included as part of the standard
    install of ruby on Windows. This gives a savings of at least 10MB.
- Removes generated docs for gems freeing up 9MB.