Updates to bring in line with latest libopencm3.

Built against locm3 commit 90172f9d72c2fcafa4701609ddfc6d65cfb84994.
Tidying up stm_flash and updating for latest libopencm3.
Merge branch 'master' of github.com:cbeighley/Swift-Nav-Code

Conflicts:
	src/hw/stm_flash.c
Added "init" function and cleaned up Makefiles.

Reduces duplication between tests.
flash_test now calls only spi_setup instead of swift_nap_setup