Some encoding fixes

[mehmetminanc]

Summary

• Fixes encoding issue when JSON is serialized.

• The current code ASCII encodes Unicode characters in UTF-8 message. Which is suboptimal.

• Simplifies travis flow, adds requirements file.
• The test cases looks funky because of the way json lib handles encoding.

Description

I was actually diving deep into some issue where the message Pijamalı hasta yağız şoföre çabucak güvendi loses its unicode characters, but noticed that the encoding was off in the request sent to the API, through Fiddler. This is not the source of the problem but I think a minor improvement is due.

Testing

• Unit tests.
• Local tests with personal account, requests routed to monitoring proxy.
  • Executed with Python 2.7 and 3.8.
  • Using Turkish and Japanese text.