Perform a validity test on `accounts.js` before trying to import it

[Nightfirecat]

Javascript is more often than not able to read local files from a user's filesystem. (ref: http://stackoverflow.com/questions/14446447/javascript-read-local-text-file) Using a method like this, we should validate the file and try to provide useful error messages if something looks wrong. (illegal characters, invalid formatting, etc.)

[atomizer]

If reading local files would work I wouldn't bother making it a .js in the first place - a simple text file would work just fine. Maybe something changed over the years, but Chrome would refuse to read anything from local filesystem - every file is considered it's own origin, see [1] [2].

[Nightfirecat]

I believe that's an artifact of the old proprietary methods used by jQuery, and security implementations by browsers. (because at that point, there was no collective effort to develop the JS API to access filesystems in a secure way)

I like the idea of moving away fro a JS file, but doing so and breaking the experience for users who currently use the JS files may not be ideal. Should file writing also be available, maybe a conversion script should be run/included with this change.

[Nightfirecat]

Update: looks like every major browser supports the FileReader API, which would do the job. http://caniuse.com/#search=FileReader%20API

I may do some work on this in the near future; would love to kill the fancy quotes problem.

[Nightfirecat]

Well damn, looks like that only works if you select a local accounts file with <input type="file">. Not really feasible when you'd rather have the accounts loaded on page load with no input.