Fix: Re-factor how credentials are handled to back-end server requests

Move code for setting username and password from endpoints.js to ajax.js
Change names of variables to not be marketplace-specific
Do not set Authorization header unless credentials are present
fix-Prohibit Basic Authentication for non-SSL connections

Since use of Basic authentication is vulnerable to man int he middle attacks for clear-text sessions, do not provide the
Basic authentication credntials for Ajax requests for which the URL indicates a non-SSL connection.
feature: handle realitve URL

When checking AJAX requests to ensure that HTTP Basic authentication credentials are not sent in the
Authenticate header for non-HTTPS requests, resolve relative URLs to an absolute URL and check the
protocol, rather than treat requests with relative URLs as non-HTTPS requests.
fix: remove unnecessary parameters to Ajax call

Removed some instances in endpoints.js where authentication credentials are being passed to the Ajax call.
The Ajax call determines authentication credentials internally, ignoring credentials passed in as
parameters to the ajax constructor.
Rebased from master
Merge pull request #172 from ozone-development/feature-basicAuth

Feature basic auth