Hook up TravisCI/AppVeyor

[jumpinjackie]

AppVeyor:

• Use VS 2017 image (hope it has v140 toolset, otherwise fallback to VS 2015)
• Grab the instantsetup bundle of the latest MGOS release and spin it up
  • Grab the matching "buildpack" for this release (need to prepare this)
  • Grab and install SWIG 3.0.12
• Do the main build/test
  • envsetup.cmd <major> <minor> <patch> <rev>
  • build.cmd
  • Build/run the .net test suite

TravisCI:

• Use ubuntu14 x64 image if available
• Use official ubuntu install script to headlessly install latest MGOS release and spin it up
  • Grab and extract headers from the "buildpack" for this release
  • Grab/build/install SWIG 3.0.12 (swigsetup.sh)
• Do the main build/test
  • ./envsetup.sh
  • make on src/Bindings/DotNet
  • Build/run the .net test suite