contiki: work without running configure

When building with contiki, 'CONTIKI' is defined and is used to detect contiki.
Configure options can be configured with:

    DTLS_CONF_ECC, DTLS_CONF_PSK, DTLS_CONF_NDEBUG

All files now include 'tinydtls.h' instead of 'dtls_config.h'.

Change-Id: I9a558a7d6bd777656d7b29028852bfc08911b8b7
Signed-off-by: Gaëtan Harter <gaetan.harter@inria.fr>
6 files changed