Client enhancements to get crtime, file magic, and PE headers data

I used MSYS2 with MINGW to build libgnurx-0.dll and magic1.dll for Windows to be able to properly use python-magic.  The installer would also need to be modified to include the file magic database magic.mgc in the client installed directory.

I removed some packing detection and checksum comparison due to it having a pretty significant performance hit on larger binaries.  It may be worth it to enable those via options when a flow is run.

This also carves off the PKCS7 certs on PE files and returns them.  There might be better ways to do this.
For libmagic it might be ok to read the first header but for pefile you really can not read the entire file into memory - and PE parsing requires randomly accessing arbitrary offsets within the file (as you walk the section headers) e.g. if you want to extract version info etc.

Why use pefile when Rekall has a perfectly good PE parser already? It also supports working on a file like object.