new subcommand exec
enable remote_command to run multiple instance
Merge pull request #373 from higanworks/new_subcommand_exec

Add new subcommand 'exec'
make chef_zero port configurable
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.
Merge pull request #397 from jtgiri/chef_zero_port

make chef_zero port configurable
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
Merge diverging branch 'master' back into spec-coverage.

Conflicts:
	lib/kitchen/cli.rb
	lib/kitchen/driver/ssh_base.rb
	lib/kitchen/generator/init.rb
Add spec for sleep/retry in SSH#establish_connection.

References #399
Remove safe_yaml config & warnings in Generator::Init.

Blocking code in Command::DriverDiscover removed in
ff1fb8a06d9502f8bb9668e2a81286202f993e74

References #416
Add spec coverage for :chef_zero_port in Provisioner::ChefZero.

References #397
Retroactively apply style/linting to master (style).