Sleep before retrying SSH#establish_connection.

This addresses a race condition where the remote instance might be
restarting its sshd process and is therefore unavailable for a second or
two.
install driver gems with Gem::GemRunner
disable safe yaml for driver gem loading
add explaination/when can be removed
Merge pull request #416 from mcquin/gem_runner-install-driver

Gem runner install driver
Merge pull request #399 from test-kitchen/ssh-retry-sleep

Sleep before retrying SSH#establish_connection.
help_update: Modify the kitchen help information for the commands that
change instance state.

help_update: Change the help test message for failed execution.

help_update:Fix spelling

help_update: Fix formatting for rubocop errors.
Merge pull request #450 from MarkGibbons/help_update

Help update
typeo confiuration -> configuration
Merge pull request #457 from michaelkirk/patch-1

typeo confiuration -> configuration