[FS#815] dnsmasq: option to create static DNS entries for static lease entries by default

[LEDE Bugs]

A new Flyspray task has been opened.  Details are below. 

User who did this - Jonathan Liu (net147) 

Attached to Project - LEDE Project
Summary - dnsmasq: option to create static DNS entries for static lease entries by default
Task Type - Feature Request
Category - Base system
Status - Unconfirmed
Assigned To - 
Operating System - All
Severity - Low
Priority - Very Low
Reported Version - Trunk
Due in Version - Undecided
Due Date - Undecided
Details - Commit 8f526ff53067d029f42e0b887d770b28546fc0e9 added the ability to create static DNS entries from static lease entries by setting the dns option to 1 in the uci host entry. It is not convenient for the user however to have to manually add this option when adding static leases from the LuCI web interface.

It would be nice if the default value for the dns option could be specified.

Some possible solutions:
- Add in the dhcp config an option to specify the default value of dns for host entries. A checkbox in LuCI for this would also be useful.
- Add a more general ability to override defaults values in uci
- Add hooks so that when config is reloaded, a script can be run that will modify the uci config as needed

More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=815