Automate PyPI release of SkyApi package

[vidya88]

@olemis commented on Apr 27

Is your feature request related to a problem? Please describe.
SkyApi will be part of next release and there are no scripts to automate this process.

Describe the solution you'd like

• Build wheel packages in Travis deploy (release-* branchs only)
• Push to PyPI sandbox.
• Run test suite after downloading and installing aforementioned packages

... once this process succeeds ...

• Build wheel packages in Travis deploy (tags only)
• Push to official PyPI
• Check packages (manually?)
• If errors detected then prepare post releases to fix'em
• Document the flow for both SkyApi and PySkycoin packages

Describe alternatives you've considered
Doing this by hand is possible , but not an option ...

Additional context
There is a deploy section in .travis.yml already .