fewer globals in app setup

[shiftkey]

This PR started as an experiment to see if we can move this chunk of code from scripts.html into the rest of the client-side JS:

up-for-grabs.net/_includes/scripts.html

Lines 72 to 82 in b020dc2

	<script src="//cdnjs.cloudflare.com/ajax/libs/showdown/1.3.0/showdown.min.js"></script>
	<script type="text/javascript">
	var files = {{ site.data.projects | jsonify }};
	var projects = new Array();
	var converter = new showdown.Converter();
	for (var fileName in files) {
	var project = files[fileName];
	project.desc = converter.makeHtml(project.desc);
	projects.push(project);
	}
	</script>

This code:

• inlines all the site data on build as a JSON payload
• downloads a third-party script (blocking)
• reads all the projects and converts any markdown into HTML
• sets projects as a global object

This is immediately used inside main.js as state for the ProjectsService:

up-for-grabs.net/javascripts/main.js

Lines 13 to 15 in b020dc2

	var projectsSvc = new ProjectsService(projects),
	compiledtemplateFn = null,
	projectsPanel = null;

And projectsSvc is used in many places inside the script.

So before I look at moving that first snippet into the rest of the app, I wanted to tidy up how the app is composed using the projects global:

• wrap it in a promise to emulate asynchronously loading the projects
• explicitly pass in projectService wherever needed, avoiding the global
• reorder scripts so that the app setup still works as expected

TODO:

• CI passes
• test deploy site and confirm no regressions