Remove catch-all rescue in Driver.for_plugin (let me explain!).

Previously this method had 3 things to do:

1. call a require
2. determine the correct constant for the driver class
3. instantiate an driver object, passing in an options hash

Now there is optional driver dependency logic that is being executed and
in short, this method is less than trivial. Now we want to see the
uncaught exceptions bubble up.
Add --log-level flag to CLI for test, create, etc.

This flag should work on the following commands:

* create
* converge
* setup
* verify
* destroy
* test
* login
Support thor 0.16.0 and 0.17.0+.
Increase default aruba timeout to 15s.
Merge branch 'log-level' into 1.0
Fix thor compatability regression between 0.16 and 0.18+.
Support SSH config from #state & #config in Driver::SSHBase.

This helps support drivers like kitchen-vagrant that are given the SSH
username, port, and identity file information dynamically per-instance
rather than captured once in a user's .kitchen.yml file.

p.s. :port is also now supported, yes!
Release 1.0.0.alpha.2, better driver debugging.
Up version for development.
Rename kb officially to Busser (the 'busser' gem).
Update Kitchen::Busser to install & use busser gem.
Spec coverage for Kitchen::Driver.
Swap out Util.to_snake_case and .to_camel_case for Thor implementations.
Spec coverage for Kitchen::Util.
Document Kitchen::Util methods.
Document Kitchen::Color methods.
Add require 'bundler' to init generator.
Remove implicit Bundler dependency in `kitchen init`.
Extract .kitchen.yml to an ERB template & update box URLs.

Closes #21
Fix :require_chef_omnibus driver_config option to eliminate re-installs.

There are 4 differnt use cases or behaviors:

* `true` - the latest release will be installed. Subsequent converges
  will skip re-installing if chef is present.
* `latest` - the latest release will be installed. Subsequent converges
  will always re-install even if chef is present.
* `<VERSION_STRING>` (ex: `10.24.0`) - the desired version string will
  be passed the the install.sh script. Subsequent converges will skip if
  the installed version and the desired version match.
* `false` or `nil` - no chef is installed.