Add __version__ and __all__

[Erotemic]

Fixes #77

Adds __version__ to the fasteners package top-level namespace.

Also, while I was modifying the __init__.py file I noticed there were a bunch of noqa comments to suppress linter warnings for unused variables. If you define a __all__ variable linters like flake8 will consider these variables as used (they are defined to be publicly accessible by convention) and therefore not warn about them.

---

As an aside, I used my mkinit module to autogenerate __init__ file and then just took the __all__ variable from that. If you like writing packages that expose submodule attributes in the top-level package, mkinit can help do a lot of the work for you. In this case the result of mkinit -m fasteners --nomod is:

# -*- coding: utf-8 -*-

# Copyright (C) 2014 Yahoo! Inc. All Rights Reserved.
#
# All Rights Reserved.
#
#    Licensed under the Apache License, Version 2.0 (the "License"); you may
#    not use this file except in compliance with the License. You may obtain
#    a copy of the License at
#
#         http://www.apache.org/licenses/LICENSE-2.0
#
#    Unless required by applicable law or agreed to in writing, software
#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
#    License for the specific language governing permissions and limitations
#    under the License.

# promote helpers to this module namespace

from __future__ import absolute_import

from fasteners.lock import (ReaderWriterLock, locked, read_locked, try_lock,
                            write_locked,)
from fasteners.process_lock import (InterProcessLock,
                                    InterProcessReaderWriterLock, LOG,
                                    interprocess_locked,
                                    interprocess_read_locked,
                                    interprocess_write_locked,)
from fasteners.version import (version_string,)

__all__ = ['InterProcessLock', 'InterProcessReaderWriterLock', 'LOG',
           'ReaderWriterLock', 'interprocess_locked',
           'interprocess_read_locked', 'interprocess_write_locked', 'locked',
           'read_locked', 'try_lock', 'version_string', 'write_locked']

As I said, I only took the __all__ variable and rearanged it to be consistent with existing package formatting, but I thought I'd mention the package in case others find it useful.

[psarka]

Thank you Erotemic!