Use the common term; the "Expert Mode" never was a distinct mode of
operation anyways.

This new feature introduces the new uci section 'gluon-core.wireless' with a preserve_channels option:
 * preserve_channels (boolean)

By setting this option to 1 (true) wifi channels will be preserved during upgrades.

Fixes #574

fix typo and express sentence regarding update priority clearer

We'll soon have other output besides the images, having a single directory
for all output makes sense.

Fixes #376

the command autoupdate not work, so a fix smal fix necessary

docs: Basic site documentation
docs: Basic autoupdater documentation
docs: minimal autoupdater info
docs: bump version to 2014.2

Closes #114