permissions tweaks & moar bootstrapification

Dropped custom `.border-hdr` for overridden
`.page-header` which is now in `fauxton.less`
so usable throughout.
Indentation/whitespace cleanup.
including Fauxton variables.less; consolidated var

Added a @greyBrownLighter to accomodate the change.

This effectively removed duplication of these
variables...here...anyway.