WIXBUG:4243 - use hashes to verify bundled packages by default.
Support redirectable package cache via policy

Implements feature 4278 by defining a new machine policy for the per-machine package cache location.
Merge branch 'bug4243' of git://github.com/robmen/wix3 into develop

Conflicts:
	History.md
Merge branch 'issue4278' of git://github.com/heaths/wix3 into develop

Conflicts:
	History.md