(MAINT) Fix bug connecting to windows vagrant host

When running multiple hosts in vagrant with an linux master and windows
agent it seems that vagrant has difficulty connecting to box when the
ssh_config file contains 127.0.0.1 for the host. This change fixes the
issue by replacing it with the host ip if it has been specified in the
nodeset.

This might need a little more manual testing.
Merge pull request #421 from liamjbennett/vagrant_ssh_config

Fix bug connecting to windows vagrant host
(QENG-1074) Override mac and win url for `install_puppet`

Previously we always downloaded windows or osx installation packages
from http://downloads.puppetlabs.com.

This allows the specifying of special urls for windows and osx to
`Beaker::DSL::InstallHelpers#install_puppet`.
Merge pull request #522 from justinstoller/allow_custom_download_urls

QENG-1074 Add options for mac and win download from alternative sources for install_puppet
(QENG-1430) Added accept_all_exit_codes option to host exec calls

QA was having issues with errors occuring when they'd like to have failures, since the specific
error codes are forseen and specific failure cases.  In order to help them with this use case,
I've added the accept_all_exit_codes option, which will not error on unacceptable exit codes,
defering to the test above to deal with the command's exit code as a failure or otherwise.
(QENG-1430) added spec for accept_all_exit_codes being explicitly set to false