test: make contiki dtls example server send package back
test: make contiki dtls example server send package back

When the contiki dtls example server receives a package, it now sends it
back to the client. This is now done like the Linux server does it.

Signed-off-by: Hauke Mehrtens <435ddd46dc66c007a1fa20144c823d37e0d23436@hauke-m.de>

thecodemaiden/tinydtls-fork,thecodemaiden/tinydtls-fork,spark/tinydtls,fvdnabee/tinydtls,thecodemaiden/tinydtls-fork,jvermillard/tinydtls,nmacs/tinydtls,spark/tinydtls,yunus/TinyDTLS-WebID,spark/tinydtls,OlegHahm/tinydtls,yunus/TinyDTLS-WebID,jvermillard/tinydtls,OlegHahm/tinydtls,jvermillard/tinydtls,yunus/TinyDTLS-WebID,nmacs/tinydtls,fvdnabee/tinydtls,nmacs/tinydtls,nmacs/tinydtls,OlegHahm/tinydtls,fvdnabee/tinydtls