Hpcc 11309 for 4.2.6

Back porting 5.0 changes to 4.2.6, comprised of 1 cherry-picked commits:

1)
commit 53afb630c01e8d8e3cc38780e9ad40cc5872f800
Author: Jake Smith <jake.smith@lexisnexis.com>
Date:   Thu May 1 19:14:06 2014 +0100

    HPCC-11309 - Ensure IDFUHelper cooperate with transactions
    
    Ensure they release their locks before committing transaction.
    Also move remove super file operation into transaction.
    
    Signed-off-by: Jake Smith <jake.smith@lexisnexis.com>