Add /MD(d) etc. build changes for CefSharp

- includes the .props include to handle builds for VS201x variants
- and the /wd4275 compiler warning disable
All this should give us four libcef_dll_wrapper.lib files ready for
CefSharp consumption for both x86/x64/Debug/Release when running
build.bat twice - for each compiler ... phew...
Make libcef_dll_wrapper.libs build with VS2013

This should be the first and last time we need this fix because it's
fixed upstream in CEF see
https://code.google.com/p/chromiumembedded/issues/detail?id=1094 - but
that is unfortunately after the official pristine binary release at
r1562
A few readme adjustments

- official location now at cefsharp team on GH
- fix a few broken links because we now have both Win32 and x64
- Mention VS2013