added high_voltage gem, in case I want to change static pages later
added style for 'back_to_top' link
moved variables method to application_controller, and removed redundant pdf-related methods from static_pages_controller
deleted links_helper.rb module, because pdfs are now hosted internally
cleaned up spec files (removed unnecessary 'subject { page }' lines, etc.)
removed redundant pdf routes
added pdfs to asset folder
changed routes to order forms on homepage to routes to pdf files
added contact page and its specs
changed links on volunteer page from external to internal pdf links
added 'back to top' link to faq