Deleted .swp and gedit backup files
Working placeholder population from /etc/config/network
Successful validation using host datatype
DNS form field should only show unique entries
Use .default, not .placeholder so overrides aren't accidentally deleted when editing other sections
Added explicit check for map save status
Fixed override removal
Merge pull request #109 from opentechinstitute/dns-override

Most recent update has been tested and confirmed working. Built a new image, re-flashed, retested.