net: added a core implementation of a FIB

Makefile.dep

sys/Makefile

sys/Makefile.include

sys/include/net/ng_fib.h

sys/include/net/ng_fib/ng_fib_table.h

sys/include/net/ng_fib/ng_universal_address.h

sys/net/network_layer/fib/Makefile

sys/net/network_layer/fib/fib.c

sys/net/network_layer/fib/universal_address.c

sys/shell/commands/Makefile

sys/shell/commands/sc_fib.c

sys/shell/commands/shell_commands.c

tests/unittests/tests-fib/Makefile

tests/unittests/tests-fib/Makefile.include

tests/unittests/tests-fib/tests-fib.c

tests/unittests/tests-fib/tests-fib.h