core/net/uip: Experimental support for loopback capability.

Enabled via setting UIP_CONF_LOOPBACK_INTERFACE to 1.
cpu/avr: Added "AVRDUDE_MCU" configuration parameter.
avr/bootloader.c: Now compatible with bootloaders which always run first.

The boot loader now knows when to go into bootstrap mode by
looking for a specific EEPROM value. Also updated code style
to match Contiki code style guidelines.
avr/radio/rf230bb: Cleanup and add hooks.

Removes references to the old rf230 code, which isn't being used
anymore.
avr/usb/rndis: Large refactoring/cleanup.

Removed a lot of jackdaw-specific stuff and made it more flexible.
cpu/avr/usb/serial: Updates to CDC serial implementation.
Various tweaks to the uip network stack.
platform/econotag: Allow RPL and Router settings to be overridden.
cpu/native: Add file-backed simulated EEPROM to native cpu.

This patch removes a defunct EEPROM implementation from the native
platform and provides a new EEPROM implementation for the native cpu.
The previous implementation appears to be vestigal.

This is useful for testing code which uses the EEPROM without running
the code on the actual hardware.

By default the code will create a new temporary file as the EEPROM
backing, reinitializing each time. If you would like to preserve the
EEPROM contents or specify a specific EEPROM file to use, you can set the
`CONTIKI_EEPROM` environment variable to the name of the EEPROM file you
wish to use instead. If it already exists, its contents will be used.
If it does not already exist, it will be created and initialized by
filling it with `0xFF`---just like a real EEPROM.

A new example is also included, which was used to verify the correctness
of the implementation. It can easily be used to verify the EEPROM
implementations of other targets.
Merge branches 'pull-requests/core-net-uip-loopback', 'pull-requests/cpu-avr-avrdude-mcu', 'pull-requests/cpu-avr-bootloader', 'pull-requests/cpu-avr-rf230bb-cleanup-hooks', 'pull-requests/cpu-avr-rndis-refactor', 'pull-requests/cpu-avr-usb-cdc-serial-update', 'pull-requests/cpu-native-eeprom', 'pull-requests/platform-econotag-uip-rpl-override', 'pull-requests/settings-for-all-targets' and 'uip-updates' into bleeding-edge
Merge branch 'pull-requests/platform-avr-ravenusb-leds' into bleeding-edge

Conflicts:
	platform/avr-ravenusb/contiki-conf.h
jackdaw: Move cdc_task and sicslow_ethernet over to ravenusbstick.

The "Jackdaw" firmware for the Atmel RZUSBStick could be very useful
on other platforms, but it's implementation is highly integrated into
the `avr-ravenusb` platform. This commit takes the first step toward
changing that, by moving the cdc_task and sicslow_ethernet code out
of the `avr-ravenusb` platform and into the `ravenusbstick` example.
platform/avr-ravenusb: Slight improvement to the RNG.
platform/avr-ravenusb: Added experimental mechanism to switch RDC at runtime.
bahhh
work-in-progress
Fix bridge mode defines
Various jackdaw updates.
cdc_task: Fix for latest RPL stuff.