1) Add version badge
2) Remove inconsistent full stops
3) Add classifiers to setup

The attempt to capture git version information is not much more robust.
If any error is raised, the error is printed, but won't break the
install. This means if, for example, git it not installed then it will
still work.

This updates to an anaconda python image and removes redundant tests
rerunning examples so that the tests finish in a more reasonable amount
of time. Many requirements are also moves to an
optional_requirements.txt file.

While lalsuite is important for many use cases, it isn't required to run
tupak.

- Convert markdown readme to rst
- Add pip install entry to installation instructions