Fix temp paths.

The path 'ShimmerDesktopDemo' is hard-coded in 'InstalledSquirrelDesktopDemo-1.0.0.zip'.
Close files before deleting.

The stream from File.OpenRead was not being disposed, causing a potential sharing violation when the temp folder was deleted at the end of the test.
Fix tests that do care about the package directory.
Merge pull request #224 from LogosBible/fix-unit-tests

Fix unit tests