Stop autofill of access key

[brendo]

While deploying a client site this week, we twice got bitten by Chrome prefilling the access key value on the Preferences page.

It would prefill this data with our Symphony password, and then as we'd save the preferences, the key would be overridden and access to S3 was lost.

This happened twice because we enabled and then disabled maintenance mode!

[nitriques]

@brendo This has already been discussed symphonycms/symphonycms#2258

The w3c spec has not changed (still only supports on and off). I've also seen people saying that it should be ="false"...

Anyways, I've created a git push hook to catch any password from being committed...

I would still be 100% for it...