This improves the Bamboo Service and provides a fix for situations,
where the build trigger won't work, because Bamboo is requiring
authentication also for the trigger GET.

The change now does provide additional HTTP Basic Auth parameters
if user credentials were provided and appends an request parameter
indicating the HTTP Basic Authentication should be used.
This aligns interaction with Bamboo with the other calls this service
executes.

Signed-off-by: Rémy Coutable <remy@rymai.me>