add megaflash and bootloader 1.7 into release tgz

fix uart init

fix REST_SetHeader, fixes jeelabs#276

try 6 to fix travis build

fix optiboot: it accumulated too much from failed attempts

use xtensa-lx106-elf-size to print section sizes

This prints more sections than the ls was and seems like a more
appropriate way to print them, the grap removes debug sections (they
address of 0) and blank lines.  This also avoids printing **, which is
the characters make uses to indicate an failure.

try jeelabs#2 to fix versioning in Makefile

try jeelabs#2 to fix versioning in Makefile

add note about boot_v1.5 bug

add note about boot_v1.5 bug