vold: don't crash when formatting unformatted volume

When formatting unformatting volumes, fstype will be NULL causing
a crash in strcmp. Set it to "vfat" to avoid the crash.

Change-Id: I3876ea2a6d91e78f579537fd6ea3d030fb18ee7b

Conflicts:
	Volume.cpp
Volume: Don't crap out when dealing with unformatted cards

And plug a memory leak when formatting them

Change-Id: I2ab58328d07a343a5ec9e1c4b58f8258f0c9133c
Avoid segv by checking argc in "storage user <mountpoint>"

Change-Id: Iffd67746e2e273c4c3f87741e5f13aa511ccb557
Signed-off-by: JP Abgrall <jpa@google.com>
default to vfat already done

Change-Id: If8819199457ba08df1432e288295990419aae004