Now playing improvements, friendlier errors, bug fixes & docs improvements

• Handle old and disconnected players properly (#28, #93)
• Handle now playing for tracks / streams with no artist (#94)
• Friendly error responses if transport is broken (#95)
• Update requests dependency for security (#96)
• Improvements to setup scripts (#100)
• Big improvements to SSL / howto guides (#104).
• Improvements to translations handling for Windows and MacOS mainly.