Fix spelling error
Minimize the amount of treatment of argv in 'cmd'

Remove some defaults and fallbacks about argv that were not used.
Because of the 'console_scripts' behavior of setuptools, 'cmd.main'
must be able to accept zero arguments and is going to read 'sys.argv'
anyway, which is also the default behavior of 'argparse'.

This breaks a use case of calling 'cmd.py' directly as a toplevel
entry point for the sake of testing, but no known parties do this.
Move pg_xlog test fixture to another file

Done in preparation to have it be shared with other integration
testing, and to communicate that it is a mechanism used by multiple
consumers (soon).
Add some black-box testing

For the first time, perform black box testing by (indirectly) calling
'cmd.main'.

The fixtures implemented here take of things like patching argv and
setting up a bucket to act as a target for the tests.

Besides improving coverage, the idea is that adding analogous
components to the class "AwsTestConfig" and then modifying
"_make_fixture_param_and_ids" will allow for easier, portable smoke
testing of more storage backend functionality.
Mock out checking for a psql binary in a blackbox test

This test is intended to exercise moving files around to S3 and back
and already goes through pains to nix integration with Postgres, so
finish the job and remove the dependency that 'psql' has to be
installed and able to log in.
Fix dangerous thinkos involving "StandardError"

StandardError is intended to include the built-in exceptions in
Python.

This was pernicious in the 'retries' module, as most errors were of
the form of timeouts, had an errno, and inherited from the built-in
EnvironmentError, yet other failure modes -- like
httplib.IncompleteRead -- would not inherit from StandardError, and
escape the retry.

Conflicts:
	tests/test_s3_deleter.py
	tests/test_wabs_deleter.py
	wal_e/retries.py