- Makes the plot_corner method an attribute of the result instance
- Removes the return of sampler from run_sampler
- Adds label and outdir to the result
- Fixes the GW150914 and BasicTutorial to run with the new interface

Fixes bug in which the uniform prior breaks when the support is an
interger value.

- Also adds matplotlib backend default to avoid issues on servers
- Shrinks psi/phase prior
- Standardish run_sampler call

For the pymultinest and nestle samplers only
- Adds equivalent parameters nlive, n_live_points, npoints etc all do
  the same thing
- Adds checking for any kwargs given to run_sampler that will not be
  used. Removes them and warns the user.

Saves the downloaded data to the outdir and, if allowed, use it as
cached data when calling again.

Reimplement spins

See merge request Monash/peyote!18

# Conflicts:
#   peyote/detector.py
#   peyote/source.py

Removes use of pickle in favour of h5 format. Uses deepdish
(https://github.com/uchicago-cs/deepdish) over the more standard
h5py for the following reasons

- h5py is built around saving 'arrays' while deepdish around saving
  dictionaries
- provides useful tools to check what data is in the h5 file
- is well written, provides good documentation and no strange error
  messages (personal experience with trying to implement h5py).

Adds bounds to power law prior

See merge request Monash/peyote!19