build: update visual studio project and fix some build issues

- adds rfc6062 patch for pjsip 2.5.5 for uwp
- updates files built by the vs project (adds some related to file
  transfer, removes those that are deprecated)
- corrects native build problems
- simplifies project layout
- links the minimal client with libdl(temp fix)

Change-Id: Ib82b0470f568cb79dc1f4353cb5a5ef20de93033