Disable the forced MD5 check
Fix mkdosfs 2GB barrier
Fix fail over to vfat from exfat

Fix issues with MD5 checking using chdir and leaving the working
dir in a subfolder that prevented unmounting sometimes.

Change-Id: I01a563d722f474297ed3f7a30064c3a61748ade3

Conflicts:
	partition.cpp
2.4.1.0