Release v2.5.0

This updates includes the following changes:

• Adds support for the initial_layout_class_list field in tokens
• Adds support for JWT X-OPENTOK-AUTH header, replacing the deprecated X-TB-PARTNER-AUTH header
• Updates the REST API endpoint URL to use /project/ replacing the deprecated /partner/
• Only include connection data in generated token if it's been defined
• Ensure backwards compatibility with Python 2.6
• Removes Python 3.2 from supported version because it's not supported by our dependency

As well as:

• Updates JS code in samples to use latest API and best practices
• Fix broken image paths in sample