Port integration tests to pytest and docstring fixes

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extra : rebase_source : d1ee0b0cfc40c440b5cf4511817ec9ea8e625d27
Skip integration tests unless --ip is given

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extra : rebase_source : 26d448e41d160371b601342ad150ca1233c1157f
Singleton code

There should only be one SoCo instance for each IP address
Check that SoCo is passed a valid IPv4 address
Deprecate SonosDiscovery and replace with discover function

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extra : amend_source : c681e5561aa9d33875b3a3476c46254dd72e1dfa
Move relevant constants to discover function. Add __repr__
Fix typos
Fix unjoin error

unjoin only requires one parameter. Current version errors. This fixes
it. Cheers David
Make to_dict return copy of content for all music data structures
Merging with recent changes in Master
deprecated speaker_ip property for backward compat. Revised __repr__ following code review
Merge pull request #91 from DPH/Fix-unjoin-error

Fix unjoin error
dedent instead of string join for PLAYER_SEARCH
Merge pull request #80 from lawrenceakka/topology

Deprecation of SonosDiscovery
Fixed flake8 complaints.
A proper LICENSE and AUTHORS file.  Add yourself to AUTHORS if I have missed you out!

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extra : source : fed10d7d0af2eccc4b0363dc391d966cf4d6c946
A proper LICENSE and AUTHORS file.  Add yourself to AUTHORS if I have missed you out!
Merge pull request #107 from petteraas/lint_fixes

Fixed flake8 complaints.
Fix rst formatting
Updating README, and convert to rst

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rename : README.md => README.rst