Remove old erbium code.

Signed-off-by: Joakim Gebart <joakim.gebart@eistec.se>
Used Uncrustify and fixed Travis build errors.

Conflicts:
	apps/er-coap/er-coap-observe.c
	apps/er-coap/er-coap.h
Added function for easy block1 usage.
Fixed blocksize calculation when REST_MAX_CHUNK_SIZE != 2^x.
Added example for block1 + separate + block2.

Conflicts:
	apps/er-coap/er-coap.h
Enabled forcing CON packet for observer notifications each 20 packets

Conflicts:
	apps/er-coap/er-coap-observe.c
Update to observe-13 (cancellation).
Removed references to missing DTLS implementation.
Merge branch 'update-er-coap' into ltu

Updated apps/er-coap to the latest available at upstream master branch.