Issue 468 package configuration

Ok, this is ready to try for real.

`npm install` is key - see the revised Getting started section to see what's been added.

There's a new grunt command, with some optional parameters:
* `grunt brand`: indicate the clone's current project brand configuration, and the available choices
* `grunt brand:Blue`: configure the clone with "Blue" branding (or whatever - SpiderOak is the current other option'. This will tell you it's not doing anything if you specify the already established brand.
* `grunt brand:!`: reassert the current brand configuration, going through the whole process
* `grunt brand:-`: initialize the default brand configuration (SpiderOak brand) if and only if the clone has no current brand configuration. If there is a valid, established brand, this just tells you that there already is, and what it is. (This is done at the end of `npm install`, so that installing ensures brand configuration.)

I am part way through updating the white-label documentation, will finish that next.

Fixes issue 468