Config Setup Tweaks

* API: Rest transport errors are now properly converted to SoftLayerAPIErrors
* CLI: Since all unknown exceptions have the traceback printed out, there's no reason to re-raise ValueError and KeyError in core.
* CLI: Adds timeout to `sl config setup` client
CLI: `sl config setup` defaults to public endpoint if no input is given
CLI: Retry username and api key/password prompts until non-empty in config setup
Consistency Updates/Puts CLI more on par with API in docs

* Moves auth handlers to its own module
* Made CLI and API landing pages in the docs. The primary index links to those pages and little else.
* Links to both the CLI and API landing pages in the README.md
* Fixes several spacing inconsistencies in the docopt sections
Moves auth tests to its own file
Merge pull request #141 from sudorandom/v3

Consistency Updates/Puts CLI more on par with API in docs
Changed the command_name to have a default of none and then checked to see if command is specified before using it. This will allow us to have modules without commands. This is useful for modules that only have one command or purpose.
Merge pull request #124 from jakew1ll/commandless

Allow command-less modules
Merge pull request #137 from sudorandom/config_tweaks

Config Setup Tweaks