(maint) Fix paths with spaces in Windows acceptance setup
Without this change, acceptance tests will fail if puppetconfdir
contains a space. This wasn't a problem previously because Beaker uses
cygpath to generate DOS-style paths, such as
C:/PROGRA~3/PuppetLabs/puppet/etc. It has become a problem during
testing of new AIO agent paths, that contain spaces in Windows Server
Fix handling of paths with spaces by quoting them when they're used.