Solidify Client Construction

[sudorandom]

I want to make the following changes:

• Rename SoftLayer.API.Client to SoftLayer.API.BaseClient
• Remove all other arguments from SoftLayer.API.BaseClient except for:
  • transport
  • auth
• Transports will now be constructed with endpoint_url, timeout, proxy and user_agent
• a new create_client_from_env() function will take all current arguments as SoftLayer.API.Client's init arguments and behave the same. It will also have an alias to SoftLayer.API.Client in order to maintain backwards compatibility. Using SoftLayer.API.Client will be deprecated.

This accomplishes the following goals:

• Generally, removes magic from initialization of an API client
• Allows for the construction of an API client without possibly loading environmental and file-based configuration options. The fact that this isn't possible has lead to initializing of a client only to set the auth handler to None since it was automatically set by reading config file.
• Makes transport-specific defaults for timeouts, endpoints, etc happen in an intuitive place.