[RENAME] bundleToUse > baseDirectoryToUse
[NEW] "version.txt" in jekyll directory (to get base version #)
rearrange: only show sync bar if we're actually doing a download
[NEW] DT 2013 app icon (had to fiddle with it a bit)
[CHANGE] update fetching to parse JSON into dict instead of simple string file; compare version numbers.
Make update check off main thread (async)
[CHANGE] ZipDownloader to take a URL from the main VC as argument for downloading zip