Add long description, classifiers and update info in setup.py

[jacobtomlinson]

Description

I was checking out warehouse and spotted that on the new pypi opsdroid page there is no description and other info. This PR updates the setup.py to add a long description, classifiers (chosen from here) and update other general info.

Fixes NA

Status

READY

Type of change

• Documentation (fix or adds documentation)

How Has This Been Tested?

Running python3 setup.py install succeeds.

Checklist:

• I have performed a self-review of my own code
• New and existing unit tests pass locally with my changes

[codecov]

Codecov Report

Merging #465 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff          @@
##           master   #465   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files          18     18           
  Lines        1095   1095           
=====================================
  Hits         1095   1095

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[FabioRosado]

I still use the old website so I haven't noticed this issue, well spotted!
I also like the new keywords to identify opsdroid 👍