Add the concept of a "Default Client" to simplify calls that require a client as a starting point

[SLsthompson]

In Pull Request #19, cbreden suggested:

Since most people will be working with a single softlayer_client, it might be worth building out some class functions to give people some shortcuts when only one client has been instantiated with a single API user/key combo. For example, getting a specific virtual guest could then become:

--- def self.server_with_id(softlayer_client, server_id, options = {})
---   service = softlayer_client["Virtual_Guest"]
+++ def self.server_with_id(server_id, options = {})
+++   service = options.has_key?(:softlayer_client) ? softlayer_client["Virtual_Guest"] : SoftLayer::Client["Virtual_Guest"]

This probably has the highest amount of impact to the current code base, but there will be some major savings from not tracking a "softlayer_client" variable at all times. This is just one way I could see this being implemented too. Opens up the ability to use cleaner code like this later:

SoftLayer::VirtualServer.server_with_id(3556842)   # -> {gets new server instance with id 3556842}

[cbreden]

It didn't dawn on me until looking at 47a994b that there's another pattern we should have considered.

Projects like fog and ridley return a client object upon initialization that has a "object-reference-pass-thru" layer (not sure what else to call it). It invokes services through the parent's client properties. Essentially, you could almost say the semantic object models are sub classes of the client object.

End of the day, it's still just another way to store a pointer back to the client properties we need. But since this pattern is used in other popular projects, should we mimic it? Here are a couple of fog and ridley examples just for reference:

ridley = Ridley.new(
  server_url: "https://api.opscode.com/organizations/ridley",
  client_name: "reset",
  client_key: "some key data",
)
ridley.role.all #=> [
  #<Ridley::RoleObject chef_id:motherbrain_srv ...>,
  #<Ridley::RoleObject chef_id:motherbrain_proxy ...>
]

sl = Fog::Compute[:softlayer]  # credentials stored in ~/.fog
sl.servers #=> list all servers
sl.servers.size #=> get a count of all servers 

Should we have gone with something like...

client = SoftLayer.new( ...parameters... )
client.virtual_guest.find_servers()

...with virtual_guest getting us to a static reference to SoftLayer::VirtualServer that we can use?

[SLsthompson]

It certainly looks like someone interested in implementing a FOG-like or Ridley-esque interface could create one very easily using the methods in the SoftLayer API that we already have.

I think this is something that can be added later without too much trouble.

[cbreden]

Fair enough!