luci-app-dawn: Bug fixes for JavaScript implementation

Some bug fixes and a small improvements that were discovered after the
initial implementation of the JavaScript version of luci-app-dawn:

* Correctly show multiple APs per client in the hearing map
* Display correct name of all APs in the hearing map
* Show if client is connected to the network in the hearing map. This
  replaces the column for Stations Connected, which is not a property
  of a client but of an AP, and is available still in the network overview.
* Display both hostname and MAC address for clients/APs
* Convert spaces to tabs in dawn-common.js for consistency

Signed-off-by: Daniel Vijge <danielvijge@gmail.com>