Bug: Breadcrumb returns empty div when no breadcrumbs

[alana29s]

While setting up Breadcrumbs for law https://github.com/bu-ist/r3-law/pull/114, it was discovered that the breadcrumbs function returns an empty div(element chosen) when there are no breadcrumbs. It would be preferable to return an empty string instead. If that may break something, a new option to return an empty string could be added.

Sample code from r3-law

						$breadcrumb_args = array(
							'glue'            => ' / ',
							'container_tag'   => 'div',
							'container_id'    => '',
							'container_class' => 'bu-banner-breadcrumbs',
							'anchor_class'    => 'crumb',
							'crumb_current'   => false,
							'anchor_current'  => false,
							'echo'            => true,
							'include_hidden'  => true,
						);

						bu_navigation_breadcrumbs( $breadcrumb_args );
					}