Convert README from MD to RST

With sphinx we'll have to write the documentation in restructuredtext
anyway, so we might use it for the README as well.

REDAME.rst

@@ -1,4 +1,16 @@
-# Introduction
+.. image:: https://travis.ci.org/pyradius/pyrad3.svg?branch=master
+    :target: https://travis-ci.org/pyradius/pyrad3
+.. image:: https://coveralls.io/repos/github/pyradius/pyrad3/badge.svg?branch=master
+    :target: https://coveralls.io/github/pyradius/pyrad3?branch=master
+.. image:: https://img.shields.io/pypi/v/pyrad3.svg
+    :target: https://pypi.python.org/pypi/pyrad3
+.. image:: https://img.shields.io/pypi/pyversions/pyrad.svg
+    :target: https://pypi.python.org/pypi/pyrad3
+.. image:: https://img.shields.io/pypi/dm/pyrad.svg
+    :target: https://pypi.python.org/pypi/pyrad3
+
+Introduction
+============
 
 pyrad3 is an implementation of a RADIUS client/server as described in RFC2865.
 It takes care of all the details like building RADIUS packets, sending them and
@@ -7,26 +19,26 @@ decoding responses.
 This is the successor of pyrad. It is written in python3 only (python3.7+) and
 has an improved API.
 
-## Requirements & Installation
+Requirements & Installation
+===========================
 
 pyrad requires Python 3.7 or later. Currently no external dependencies are
-needed to use pyrad3.
+needed to use pyrad3:: cli
 
-```cli
-# Install from pypi
-pip install pyrad3
+  # Install from pypi
+  pip install pyrad3
 
-# Install from the repository
-git clone https://github.com/pyradius/pyrad3
-pip install .
+  # Install from the repository
+  git clone https://github.com/pyradius/pyrad3
+  pip install .
 
-# Installing with poetry
-git clone https://github.com/pyradius/pyrad3
-poetry install --no-dev # for usage; without optional dev dependencies
-poetry install # for development
-```
+  # Installing with poetry
+  git clone https://github.com/pyradius/pyrad3
+  poetry install --no-dev # for usage; without optional dev dependencies
+  poetry install # for development
 
-## Development
+Development
+===========
 
 pyrad3 usese quite a lot of linters and development tools:
 
@@ -52,17 +64,20 @@ When poetry is installed, the development dependencies can be installed with
 install pyrad3 itself.
 
 
-### with nix
+with nix
+--------
 
 
-### Generating the documentation
+Generating the documentation
+----------------------------
 
 Sphinx is used for the documentation. It can be either run directly with
 ` ` or with `make` (requires `gnumake` to be installed.)
 
 TODO: no documentation yet.
 
-### Running tests locally
+Running tests locally
+---------------------
 
 pyrad3 comes with a tox configuration (check the `[tool.tox]` section in
 ./pyproject.) Tox will set up test environments for all supported python
@@ -73,11 +88,12 @@ It is necessary that the python versions are installed otherwise tox will fail.
 To execute a test with a single python version run `tox -e $version`, e.g.
 `tox -e py38`.
 
-## License
+License
+=======
 
 pyrad3 is distributed under the terms of both the MIT License and the Apache
 License (Version 2.0).
 
-See [LICENSE-APACHE](LICENSE-APACHE) and [LICENSE-MIT](LICENSE-MIT) for
+See `LICENSE-APACHE ./LICENSE-APACHE` and `LICENSE-MIT ./LICENSE-MIT` for
 details.