doc: add zerocloud auth config guide

This adds auth config documentation for both v1 and v2 auth schemes for
Swift/ZeroCloud.
Merge pull request #96 from larsbutler/swift-auth-docs

Swift/ZeroCloud auth docs
zpm: only accept "1.0" and "2.0" as auth versions
zpm: avoid changing type of version variable
deploy: let argparse handle invalid auth version
Merge pull request #99 from mgeisler/auth-version

Simplify auth version handling
new: default to "." instead of the full os.getcwd

This give us smaller relative paths in the output and lets us include
the default in the help generated by argparse (including the full
absolute path returned by os.getcwd would vary depending on where the
user runs 'zpm new -h'.)
deploy: standardize default in cmdline help texts

We now use %(default)s where possible to let argparse insert the
correct default in the help text.

The flags that default to an environment variable list the environment
variable instead of the actual value -- listing the default would not
be helpful when the environment variable isn't set (it would be the
empty string).
Merge pull request #100 from mgeisler/default

Cleanup cmdline flag default values
help: add help command

This command will work similarly to 'hg help' or 'git help'.
help: handle command specific help
doc: add help command to command list
help: split command docstrings into summary and description

The first line of the docstring is the summary and it is used as the
help text for each sub-parser. This is shown in 'zpm -h'.

The other lines of the docstring is used as the description of the
subparser. This part is shown by 'zpm CMD -h'.
new: add summary line to docstring
Merge pull request #102 from mgeisler/improve-help

Improve command-line help
deploy: "not all(not x)" is the same as "any(x)"

As per the comments in #93.
setup: move version string to zpmlib
doc: use version number from zpmlib
version: new command for showing version number (#103)

This comes with a little test that should remain stable as the version
number changes in the future.
zpm: add support for --version flag (fixes #103)

This uses the special 'version' action in argparse. In Python 2.7 and
later, argparse automatically supplies a suitable help text, but not
in Python 2.6. We therefore specify the help text ourselves.