Some documentation clarification.

I got bit by the expectation of a particular file in .ssh (I have multiple keys, but none are named using the default).
Remove the setting from other branch.
Add two new configuration options, RE: TCP checks

This commit adds two additional configuration items:
```
+      default_config :ssh_sleep, 120
+      default_config :no_ssh_tcp_check, false
```

If `no_ssh_tcp_check` is true, `wait_for_sshd(state[:hostname])` will be skipped after sleeping for `ssh_sleep` seconds (default sleep of 2 minutes). These changes are required until test-kitchen can read complete SSH configurations, including any proxies or other overrides.

Exposing this new option isn't specific to Rackspace. These settings have been added to control a behavior in kitchen-rackspace (calling a method in test-kitchen that performs a TCP check) that otherwise has no way for the user to control. While that method should probably be removed/fixed from test-kitchen (or made to actually test SSH functionality rather than TCP connectivity), it's actually kitchen-rackspace that is calling it (and should at least allow an override for the behavior). And it's broken for everyone who requires any kind of SSH bastion or proxy command.
Merge pull request #28 from martinb3/documentation_update

Some documentation clarification.
Fix #18
Merge pull request #30 from test-kitchen/roboticcheese/replace-latest-with-true

Fix #18
Add unit tests for new functionality and update changelog
Merge pull request #32 from test-kitchen/roboticcheese/add_tcp_settings

Add two new configuration options, RE: TCP checks
Added functionality for users to specify networks

- This commit allows a user to specify optional additional networks,
  allowing them to join their test servers to a user-created network
  inside of Rackspace.

- By default, all servers are joined to PublicNet
  ('00000000-0000-0000-0000-000000000000') and ServiceNet
  ('11111111-1111-1111-1111-111111111111').

- To save users from having to specify these two mandatory networks, the
  method #rackpsace_networks will simply append these two networks to
  whatever networks the user has specified in the kitchen.yml file.

- Appropriate, but slightly honey-badger (what law of demeter?) specs
  have been added for this new functionality.

- This has been tested by me and a couple of other users in my company.
  It probably works.

Updated README to include networks: stanza.

Clean up slightly abusive trace message.

Make RuboCop happ(ier).

- I really don't know how to trim this down to 100 lines. Any ideas?
Do a little cleanup for RuboCop
Merge pull request #33 from test-kitchen/roboticcheese/custom_networks

Support custom networks
Bump version for release
Bump version for dev