wait for device creation; minor fixes
wait for device creation; minor fixes

 * use the udev sync foo to make sure that nodes appear before
   continuing. This is particularly important when trying to create
   stacked volumes for the cascaded ciphers.

 * add a newline char to the "All Ok" printf.

 * don't mistakenly return that everything went ok in dm_setup when the
   only thing that went ok was the unrolling of changes after an error.

bwalex/tc-play,veracrypt/tc-play,Nmishin/tc-play,veracrypt/tc-play,bwalex/tc-play,bwalex/tc-play,Nmishin/tc-play,veracrypt/tc-play,Nmishin/tc-play