Explain Query - Expand/Collapse Rows

Address Issue #57

+/- shown regardless if row will actually expand; Can add enhancement to show/hide button based on DOM element height later.

![explain_query___acs_aem_tools_and_acs-aem-tools__acs](https://cloud.githubusercontent.com/assets/1451868/3729909/d60930ba-16c5-11e4-9220-4c3b45d2af88.png)