Added sanitizeHtml function to Homebrew model to generate HTML from the brew for the source page.

Moved `source` page generation function to a new function module. Added option to function to create plain text download with a sanitized filename and made it accessible from a new page: `download`.
Added the `download` item to the BrewItem so it appears on each brew on the User page.
Added `sanitize-filename` dependency to `package.json`.

client/homebrew/pages/sharePage/sourceFunctions.jsx

@@ -0,0 +1,56 @@
+const HomebrewModel = require.main.require('./server/homebrew.model.js').model;
+const sanitizeFilename = require('sanitize-filename');
+
+const shareFunction = function(req, res, type) {
+	if(req.params.id.length > 12) {
+		const googleId = req.params.id.slice(0, -12);
+		const shareId = req.params.id.slice(-12);
+		GoogleActions.readFileMetadata(config.get('google_api_key'), googleId, shareId, 'share')
+		.then((brew)=>{
+			if(type == 'source') {
+				return res.status(200).send(brew.sanitizeHtml());
+			} else if(type == 'download') {
+				let fileName = sanitizeFilename(brew.title);
+				fileName = fileName.replaceAll(' ', '-');
+				res.status(200);
+				res.set({
+					'Cache-Control'       : 'no-cache',
+					'Content-Type'        : 'text/plain',
+					'Content-Disposition' : `attachment; filename="HomeBrewery-${fileName}.txt"`
+				});
+				return res.send(brew.text);
+			} else {
+				console.log('Unhandled source share type');
+			}
+		})
+		.catch((err)=>{
+			console.log(err);
+			return res.status(400).send('Can\'t get brew from Google');
+		});
+	} else {
+		HomebrewModel.get({ shareId: req.params.id })
+			.then((brew)=>{
+				if(type == 'source') {
+					return res.status(200).send(brew.sanitizeHtml());
+				} else if(type == 'download') {
+					let fileName = sanitizeFilename(brew.title);
+					fileName = fileName.replaceAll(' ', '-');
+					res.status(200);
+					res.set({
+						'Cache-Control'       : 'no-cache',
+						'Content-Type'        : 'text/plain',
+						'Content-Disposition' : `attachment; filename="HomeBrewery-${fileName}.txt"`
+					});
+					return res.send(brew.text);
+				} else {
+					console.log('Unhandled share type');
+				}
+			})
+			.catch((err)=>{
+				console.log(err);
+				return res.status(404).send('Could not find Homebrew with that id');
+			});
+	}
+};
+
+module.exports = shareFunction;