Umobj

This release officially supports Python 3. 🎉 🎉 🎉

Features/changes:
* `cpobj` now accepts multiple source files
* deprecated homebrew. Please use pip exclusively going forward.
* changed the behavior of `rmobj` to be more consistent with `rm`:
* `rmobj -f` will not prompt the user if they want to delete files/directories *at all*.
* `rmobj -i` is now needed if you want to be asked about every delete operation. If you just pass `rmobj -r` you will be asked only once now.

Bugfixes:
* `rmobj` is now more selective about removing key prefixes. This means that `rmobj -rf bucket:foo` will now remove everything under `bucket:foo/*`, but not `bucket:foobar/`. Thank you to Sanghyun-Hong for reporting this bug!
* fixed a bug in `cpobj` where a single key could not be copied out of the object store with a different key name locally.
* more graceful logging of S3ResponseError for multipart uploads
* implemented better error messages if invalid credentials are being used
* the exit statuses in `rmobj` are now consistent with the behavior for `rm`. The exit status will be non-zero if there were failures removing something unless `-f` is specified, in which case the exit status will always be zero.

This is mainly a bug fix release with a new feature thrown in as well!

Features:
- Use `cmpobj -d` to compare a local directory to a bucket. This will tell you what files exist locally but not remotely, remotely but not locally, and which files that exist in both locations contain differing content. (raushan802)

Bugs:
- `lsobj` now catches all exceptions that can be thrown when getting or creating a bucket.
- Fixed an issue with `cpobj` throwing I/O errors when writing a file whose parent directory does not exist locally yet. This bug would manifest itself when the empty keys representing the parent directories of a key were missing.
- strip the OS path seperator (i.e. "/") from the right-hand side of a key name before checking for existance of key if the recursive option was not specified
- Wrap calls to delete keys and the bucket in rmobj so that we can catch errors more reliably and log them appropriately.

- Added `streamobj`. This allows streaming uploads to an S3 storage entity without having to create an intermediary file. E.g. `tar -cvf - myfiles/* | streamobj -n filearchive.tar mybucket:myfolder`
- `lsobj` now defaults to just printing key names with no metadata. Pass the `-l` flag to gain the old behavior.

This is the first widely-available (open-source!) release of the umobj utilities.