Initial implementation for pagefile support on windows.

* Winpmem can now also acquire the pagefile.

* Rekall can perform windows specific PTE resolution. Including Prototype PTE, VAD PTE, Subsection PTE and Pagefile PTE.

* Added new plugins to inspect page mappings:
   vadmap: Display all mappings in every page of the VAD
   pte: Analyse PTE and follow Prototype PTEs
   vtop: Updated to support full PTE resolution.

BUG=
R=amoser@google.com

Review URL: https://codereview.appspot.com/159400043