fix(client): KeyError on cookie retrieval

Fixed an issue where 'no active controller' message didn't show if
cookies didn't already exist.
docs(reference): update client reference link

The client documentation should handle an internal link to client,
while the client reference should also get its own. There are no
known links to the client reference docs, so no other changes are
necessary at this time.
docs(reference): update reference guide
docs(reference): use deis <command> as title

This makes it such that when you reference the command in the
documentation as ":ref:`deis_releases`", it shows up as "deis releases".
ref(docs/reference): aggregate client commands
style(docs/reference): missing period
test(controller): disallow blank container types

We do not use this feature. Removing it increases our test coverage.
Merge pull request #1041 from deis/blank-container-types

test(controller): disallow blank container types
Merge pull request #1350 from deis/1254-cookie-error

fix(client): KeyError on cookie retrieval
Merge pull request #1327 from deis/fix-reference-guide

fix(docs/reference): the big reference guide refactor
feat(client): add config:pull command

This command pulls in existing config variables set with deis
config:set and writes them out to a local .env file for
development purposes.

If a .env file exists and a environment variable in that file is
present in the application's config, the file's envvar will be
chosen unless the --overwrite option is selected. If
--interactive is present, a prompt to write the environment
variable to the file will be shown.

fixes #560
refactor(client): alphabetize command shortcuts
docs(reference): add config:pull to autodocs