(doc) Update release notes for 0.9.8.24

 - Updated changelog
 - Updated chocolatey.nuspec (need to add some automation for these to pull
   from somewhere when building the package)
Merge branch 'stable'

* stable:
  (doc) Update release notes for 0.9.8.24
v0.9.8.24-beta2
Merge branch 'stable'

* stable:
  v0.9.8.24-beta2
add tests for Chocolatey setup (Initialize-Chocolatey)

Note: the tests assume the test suite is run with administrative rights
(i.e. elevated).
setup tests: mock UAC status
Add Test-AdminRights helper
Enable mocking Test-AdminRights for setup tests
setup tests: add simulated standard user scenarios
fixup - add more std user tests
fixup - user tests formatting
fixup - remove duplicate admin uac test
fixup - std user tests with explicit path
setup tests: with admin rights, set variables at Machine level regardless of UAC
when running with administrative rights, set environment variables at Machine scope

The CurrentPrincipal::IsInRole(Administrators) check is sufficient to
ascertain administrative rights, whether UAC is enabled or not.

In particular, if UAC is enabled, this check will only return true if
running elevated.

This change enables per-machine installation on systems with UAC enabled
(only if the user installs/invokes Chocolatey from an elevated shell, so UAC
prompt is not triggered), while not disrupting the behavior for standard users.
setup tests: do not vary by UAC status
setup tests: fix formatting and descriptions