Fs.sshfs

Added
- Extraction of user/group with `uid`/`gid` if remote platform is Unix.

Changed
- Switched to `green` to run tests in CI environment.

Changed
- Added opener entry points to `setup.cfg` to be compatible with the new
plugin architecture for FS URL openers.

Fixed
- Typo in `README.rst`.

Changed
- Make `setuptools` build version-specific wheels.

Changed
- Use `setup.cfg` to configure the project installation.
- Dynamically load version of the installed package in `fs.sshfs` and
`fs.opener.sshfs` instead of hardcoding it in a file.

Fixed
- `nosetests` mistaking base `TestSSHFS` for a test case.
- `nosetests` requiring `rednose` as a setup requirement.
- Typos in `README.rst`.

Added
- Heuristic to guess the server platform using either `uname` or `sysinfo`.

Changed
- Use custom function to extract `info` and `details` from `status` results
instead of using the builtin `OSFS` one.
- Use plain enums instead of `enum.Flag` to record the server platform.

Fixed
- Invalid license classifiers in project metadata.

Initial release.