Fix HttpAttributeEnricher that always assumes the full Http url to be set

[avinashkolluru]

Problem: HttpAttributeEnricher works with the assumption that the full http url is always available in the span which is not true. (See #99 for more details)

This assumption should be fixed and we should work with just the path and query strings that are available if we get only the relative url.

[avinashkolluru]

Fixed #112