(GH-425) Sleep after killing processes

This avoids a race condition in which the killed processes haven't
exited by the time we try and unmount the root fs and the call to
container.delete errors.
(QENG-1182) Add node to classifier prior to adding pe_repo class

Prior to this commit, beaker would make the assumption that a node had
already checked into the classifier. This commit changes that by
ensuring that the node is in the classifier before giving it the pe_repo
class.
Merge pull request #443 from briancain/maint/master/add-node-to-classifier

(QENG-1182) Add node to classifier prior to adding pe_repo class
(maint) Bump version for 1.17.7 release
Merge pull request #444 from branan/ship_1_17_7

(maint) Bump version for 1.17.7 release
(QENG-1186) Fix Beaker::DSL:Helpers.puppet_{user,group}

Looks like the contents of these methods were mixed upwhen originally written.
Luckily the puppet user is usually the same as the puppet group.

Signed-off-by: Wayne <wayne@puppetlabs.com>
(QENG-797) Enhance Beaker to look for x64 installers for Windows

- add ability to install 64 bit pe builds (available for pe 3.4)
- add is_x86_64? method to host, convenience method for determining arch
  of host
(QENG-1026) Add support for x64 PE windows to Beaker

- default to installing 64 bit builds on 64 bit windows
- support install_32 host option, true = install 32 bit no matter the
  arch, false/unset = install 64 bit on 64 bit, otherwise 32 bit
(QENG-1129) support win64 open source builds

- add ability to install 64 bit windows builds
- supported when puppet version is 3.7+ or pe is 3.4+, and install_32 is not set for
  host or globally
- correctly update path post pe/puppet installation
Merge pull request #436 from anodelman/win-fix

(QENG-797) Enhance Beaker to look for x64 installers for Windows
Merge pull request #425 from jtopper/avoid_docker_clean_race

(GH-425) Sleep briefly after killing processes - Docker
Merge pull request #445 from waynr/fix/qeng-1186-beaker-dsl-helpers-puppet-mixup

(QENG-1186) Fix Beaker::DSL:Helpers.puppet_{user,group}
(QENG-1146) Add vagrant_fusion, vmware_workstation, and vagrant_virtualbox providers

Currently the vagrant hypervisor provider just does virtualbox. This
allows the vagrant vmware_fusion and vmware_workstation plugins to be
used instead.