Add uploading of the sketch through SD

[loathingKernel]

From @loathingKernel on November 6, 2012 12:59

Since most ethernet shields have an SD card socket this might would be useful to have.
I am just leaving it here to see how many people are interested in having this feature integrated to
Ariadne.

It has been done before so, probably, i will be using the existing solution if it fits nicely with the rest of the code.

Copied from original issue: codebndr#3

[loathingKernel]

From @eliyash on December 18, 2013 22:5

hello LoathingKernel!
I am very interested...

eliahu

[loathingKernel]

From @d0ughb0y on September 10, 2014 22:19

Hi Stelios,

This will be useful addition.
I asked users of my program for feedback, and they prefer to upload bin file to sd card, then reset.
My program already has a full blown web server and takes http put uploads to SD card.

BTW, I looked at 2boots bootloader, and it stores the filename at the end address of eeprom, not at address 0. I think it is more common practice to store user data at 0, and system data at high address.

thanks.

[loathingKernel]

From @q2dg on April 3, 2015 12:25

+1 !!!

[loathingKernel]

From @FloeHerrmann on April 13, 2015 7:5

+1

[loathingKernel]

From @Apollon77 on July 22, 2015 20:3

+1, I currently try https://github.com/FleetProbe/MicroBridge-Arduino-ATMega2560

[loathingKernel]

From @q2dg on October 21, 2015 14:37

Another option is https://github.com/zevero/avr_boot