[!17, #65] Model renamed

diff --git a/src/lib/yang/models/ietf-dhcpv4-server.yang b/src/lib/yang/models/kea-dhcpv4-server.yang
similarity index 100%
rename from src/lib/yang/models/ietf-dhcpv4-server.yang
rename to src/lib/yang/models/kea-dhcpv4-server.yang