DataFlash: try to keep dataflash writes aligned

also rename lastlog.txt to LASTLOG.TXT as NuttX seems to get less
corruption with VFAT filenames that don't need uppercase mappings
Plane: use uppercase names on microSD card where possible
Copter: use uppercase names on SD card where possible
Rover: use uppercase names on SD card where possible
HAL_PX4: try to use uppercase names on NuttX microSD card
PX4: use BOOT.LOG instead of boot.log
HAL_PX4: added support for MTD (FRAM) parameters

this allows us to store parameters and waypoints in FRAM, and
auto-upgrade from microSD
DataFlash: improve reliability of microSD for logs
DataFlash: don't fsync on SITL

this makes it much faster on virtual machines
PX4: enable mtd driver in build
PX4: start mtd driver on FMUv2
Plane: make LOG_BITMASK 32 bits
Plane: only log when armed by default

use safety switch if arming not enabled