uthash.h -- minimize changes wrt. github/master

minimize changes wrt. github/master in order to allow for easy integration of github/develop

• delete header that adds info for Fokus copyright on changed code
• bring back the header -- if necessary -- once we integrated with github/master

we only changed:

• malloc() --> coap_malloc()
• free() --> coap_free()

This change should actually be propagated as a bug fix / enhancement to the upstream as the entire clap-implementation used coap_malloc() and coap_free().

So these changes are not Phoenix specific but required for us in order to consistently use the memory management that coap_malloc() and coap_free() encapsulate.

[ ] check if those changes already exist in the upstream. [ ] create patch request for upstream if changes are not present in upstream.