Releasing a new version

This project adheres to the Semantic Versioning specification by Tom Preston-Werner.

Requirements

Packages:

$ pip install -r requirements-dev.txt -r docs/requirements-docs.txt
$ pip install wheel twine

Bump version:
- telegram/__init__.py
Log changes to:
- CHANGES.rst
Run tests:
```
$ make test
```
Build source distribution:
```
$ python setup.py sdist bdist_wheel
```
Register new version:
```
$ python setup.py register
```
Upload to PyPI (-s to sign the package with your GnuPG key):
```
$ twine upload -s dist/python*
```

Commit the version bump and add tag:

$ git commit -a -m 'Bump version to v<VERSION>'
$ git push

Create a new release:
- Tag version: v<VERSION>
- Release title: v<VERSION>
- Description: <logs from CHANGES.rst>
Build documentation:
```
$ python setup.py build_sphinx
```
Upload documentation (Upload failed (503): backend read error may happen but not really an issue):
```
$ python setup.py upload_sphinx
```
Close milestones for this version.
Test in a clean virtualenv that pip install python-telegram-bot works with the new version.