Move errors.h to own directory, fix duplicate value

	renamed:    lib/utils/errors.h -> lib/errors/errors.h
Add strerror()

	new file:   lib/errors/errors.cpp
strerror(): Handle SUCCESS, get rid of useless "break;" statements

We return, anything below will never be executed.
Also add strerror() to the header file.
Get rid of ads1231_error_msg(), replace with generic ERROR(strerror())