2.8.0 - NativeScript support

Improvements:

• Added fetch API instead $.ajax() and request() (REST API support for NativeScript);
• Chat adapted for NativeScript enviroments;
• The MessageProxy and the DialogProxy were remove from qbChat.js to separate modules;

Add:

• Add stream management test cases;
• Add link on API ref. in Readme.md.

Fixed:

• Fix TypeError: Cannot read property 'statusCode' of undefined for Node env;