Move to zip.js from JSZip? Or implement JSZip within webworker?

[jthrilly]

Currently unzipping large protocol files hangs the render thread on cordova (which is single threaded) when using JSZip.

zip.js implements concurrent threaded unzip using web workers, which are supported on all platforms.

Additionally, unzipping large protocol files causes app crashes, believed to be due to memory constraints, on cordova (particularly iOS). This may help alleviate that issue.