Clamp down on VS compatibility

Merge pull request github#227 from github/feature/metrics

Collect anonymous metrics

Merge build/sign-with-sha256 into release/1.0.16.3

Merge build/sign-with-sha256 into release/1.0.16.3

Switch to sha256 certificate

Merge fixes/repository-list into release/1.0.16.1

Merge fixes/repository-list into release/1.0.16.1

Bump version to 1.0.16.0

Bump version to 1.0.15.5

Make vsix dependency version range less strict

Makes future VS versions able to support loading the extension
(backwards compatibility ftw)