added basic prerequisite tree to module page
Added .DS_Store into .gitignore
Check if module exists before modulifying
Use object lookup rather than array lookup for modules
Changed colours for ModMaven tree
More Ui tweaks
Added IVLE button to the module page
Fix bug with add module to timetable on module page
Switched the modmaven tree styles and animations to css
Merge branch 'master' of https://github.com/ahbeng/NUSMods into feature/modmaven-integration

Conflicts:
	.gitignore
	app/scripts/modules/templates/module.hbs
Fix bug of toggling mode in preferences screen doesn't behave correctly
Merge remote-tracking branch 'origin' into feature/modmaven-integration
added ivle login and module history fetching
added visual cue on the tree for non existent mods
Merge branch 'master' into feature/modmaven-integration

Conflicts:
	api
Use ivle namespace for ivle localforage keys
Tweaks to ModMaven