[js_auth_client_browser_test] tests improved to run correctly using "grunt test" command

There was a bug: browser tests did not run with 'grunt'. Problem is resolved.
Bind is used by library. 
https://github.com/caskdata/cdap-clients/blob/develop/cdap-authentication-clients/javascript/src/authmanager.js#L76
The only one alternative - is to use such a function in library code.