Replaced background progress bar with fullscreen loader, bug fixes

images/progress.gif
	-looping progress GIF that displays while content is being loaded

templates/SkillTree.html
	-backgroundProgress DIV removed
	-hiddenOverlay replaced with loadingOverlay

scripts/script.js
	-fixed possible bug in which skill tree would break when a pre-requisite was added
	-fixed ensureModuleDetails not working with additional parameters
	-createModuleBox now supports creating helper DIVs, which have no id and no functionality
	-module list and skill tree loading will now utilise the loadingOverlay DIV
	-addModuleToTree now supports adding to a specific semester
	-added support for draggable modules in the module list
Added WSGI exception handler hook for intensive server debugging
Slight alteration to initial loading text
Customised page title to match design in project poster

templates/
	-Roboto imports in all templates now import both Thin and Regular styles

css/main.css
	-added declaration for #title_header, which can adapt to any given font size.
Altered colors for title to fit poster design.