* esp-netif to optionally depend on esp-eth (only for l2tap config)
* esp_eth.h now includes the original ethernet header and the
ethernet-netif glue layer
* Updated examples and test to explicitely use esp-eth dependency if
needed
* changing dependencies from unity->cmock
* added component.mk and Makefile.projbuild
* ignore test dir in gen_esp_err_to_name.py
* added some brief introduction of CMock in IDF