Please tag and release as 7.x-2.0-beta18

PT-804 - updated call to services_error() to invoke module_include_load() first
PT-804 - updated signatures data layer to format names and locations in accordance to petitions_signatures_display settings
PT-804 - updated mongo accessor class to extend the new SignaturesBase and added new abstraction layer to the list of includes
PT-804 - updated docblocks, fixed typos and formatting, resolved dependency conflicts