New makefile component_wrapper.mk allows some variables to be set
before component.mk is evaluated. This properly fixes problems with
sdkconfig being hard to access in all phases of the build.
Including component_common.mk is no longer necessary and will print a
deprecation warning for components which use it.
This also removes logging implementation from bootloader and replaces it
with the one provided by the log component. Some occurrences of printf
and ets_printf have been changed to ESP_LOGx APIs.
Jakob Hasse