resume download after fail

/cc @cbednarski

builder/amazon-ebs: Clean up orphan volumes

/cc @pearkes - This fixes that crash

Fixes #1783

/cc @cbednarski - I try to do this after every PR just so I don't
forget, not a bad practice to get into. This is perhaps arguably an
"improvement" but I think due to the magnitude of code change I think
its worth it in the features sectin. :)

provisioner/puppet-server: Add ignore exit codes option

provisioner/shell: randomize default script name

post-processor/vagrant-cloud: retry uploads [GH-2167]

Added new compress post-processor from Vasiliy Tolstov

Refactored test so it's more DRY and also rearranged things so the test cases and configs are at the top of the file

update the documented datatype for facter to 'object of key/value str…

update the documented datatype for facter to 'object of key/value strings' for both puppet provisioners

builder/parallels: Add mock for "SetDefaultConfiguration" method

Fixes unit test failures

Parallels: Apply default settings on the VM creation step.