CONNT-29: Implemented initial set of release procedures:

- Replaced versioning on default branch tip to "dev".
- Updated the release notes to include information about changes made
since version 0.2.
- Added initial set of release procedures, covering versioning schema,
instructions on writing release notes, release issue template,
backporting of fixes, releasing new versions.

CONNT-28: Updates to documentation, requirements handling, and minor fixes:

- Fixed syntax error in MANIFEST.in file for recursive-exclude.
- Merged the about section from documentation into the README file.
Documentation now references README file instead of duplicating the
data. Minor formatting and wording fixes were made as well.
- Updated Sphinx configuration to use same string for both release and
version (deduplicate it a bit).
- Added a new, develoment-related, section to the documentation. Describes
how to set-up the development environment, as well as some maintenance
tasks.
- Updated quickstart instructions so they actually work. Switched to
using the pip install from PyPI instead of repository.
- Introduced pip-tools use for the development requirements file.
- Switched to using more fixed requirements in the setup.py.
- Removed test requirements from the setup.py.