Integrate the ceph s3-tests suite into automated client tests

Add the ceph s3-tests suite to the set of automated python client
tests. This includes a script to create 2 user accounts and populate a
config file with information for those users. Currently the master
branch of the basho fork of the test suites is used, but in the future
this should be changed to use a tag. Also for now only the
functional test suite is run.
Address s3-test functional suite failures

Fixes: #578

Address a number of issues around access, validation, and the
content of error responses that were cause failures in the s3-test
functional test suite.
Add s3-tests directory to .gitignore
Fix typo in spec definition
Update test-python target in top-level Makefile
Update expected output for 404 error in cs512 regression test
Make the s3-tests setup check for CS_HTTP_PORT
Bump webmachine dependency to the 1.10.2 tag
Merge branch 'feature/ceph-s3-test-integration' into develop