Fix satoshisPerByte and remove '.value' from examples

[bobbrodie]

Overview

This PR has two changes:

• Fixing type on satoshisPerByte
• Updating examples

Fixing type on satoshisPerByte

This is a new field that was defined as an int but needed to be updated to a float. I've tested this in a small project by pointing my pipfile to my branch.

Updating Examples

Our examples had:

client = Client.create_pos_client('somePosToken', Environment.TEST)

But that will throw an exception, so I've updated to:

client = Client.create_pos_client('somePosToken', Environment.TEST.value)