When loading icon resources, Xporter must validate if the path is missing the Base URL

When loading icon resources, Xporter must validate if the path is missing the Base URL.

This is the error that occurs when Xporter receives a malformed URL Xporter.log.

Steps to reproduce this problem:

1. Create a Jira instance with a context path
2. Add some comments to an issue with icons
3. Export the comments using a for comments. You must use the wiki function. "Issue Detail View" template has this iteration.
4. The comments with icons are not exported correctly