configurable http request agent
Merge pull request #111 from ianshward/configure-agent

Make the http agent configurable
Implement region option.
Move options documentation to the bottom and expand it.
Cleanup tests a bit.

Moved from ./auth to ./test/auth.json. Sorry for the one-time pain.
Fix #96: allow other casings for "Content-Length" in putStream.
More test cleanup.

- Use `assert.ifError`.
- No longer need to explicitly specify x-amz-acl: private.
Document the new list files operation.
Release 0.4.0
Add pointer to knox-mpu to the README.

Closes #89! Thanks @nathanoehlman!
Add support for temporary security tokens
Move `token` usage down in the README.
Release 0.4.1
Fix #121: `deleteMultiple` broken with leading slashes.
Style uniformization.
Fix a bug where `list` would make `Contents` a single object instead of an array.
Ensure we always clean up our S3 bucket.
Move Multipart Upload into a new "Beyond Knox" README section.
Add README section pointing to @superjoe30's s3-client.
Release 0.4.2