Made the technician config customisable

 * Finished defining the technician config's optional parameters
 * Updated readme.md with documentation on the new parameters
 * Moved non-technician tasks out of the technician config
 * Added webmin configuration to limit access to the technicians

Issue: IWSoftware/ekahau-rtls-playbook#1
Ticket: #5507

Signed-off-by: Nathan Callister <ncallister@iwsoftware.com.au>