Squashed commit of the following:

commit a3a7853d056f35421fba161fa5cde980c5dfe727
Author: Yang Lu <yang@voltdb.com>
Date:   Wed Jul 30 10:55:03 2014 -0400

    For ENG-6397, remove one line of duplicate error message.

commit a470a8b92c58e63a0c14e57b785545d38a2d06cf
Author: Yang Lu <yang@voltdb.com>
Date:   Mon Jul 28 15:40:23 2014 -0400

    For ENG-6397, change the default stratedy to replace the
    completion file if it already exists.

commit 0e70ce7a4dffb8ec3567dfa91e3a22f6a41926c0
Author: Yang Lu <yang@voltdb.com>
Date:   Mon Jul 28 15:27:00 2014 -0400

    For ENG-6397, change the wording of error message.

commit e4e59981d2b3739ce75784598f3916b144ac2a24
Merge: bd6e508 aa72091
Author: Yang Lu <yang@voltdb.com>
Date:   Mon Jul 21 16:49:04 2014 -0400

    Merge branch 'master' into ENG-6397-snapshot-completion-flag

commit bd6e508aa34e6ce89219b58431dccc50bce8ff05
Author: Yang Lu <yang@voltdb.com>
Date:   Mon Jul 21 11:43:52 2014 -0400

    For ENG-6397, use logger instead of system err.

commit 28653583e1776a921d71a457bcfea237b6f81cd3
Author: Yang Lu <yang@voltdb.com>
Date:   Wed Jul 16 15:49:14 2014 -0400

    Change the extention of snapshot completion file to .finished.

commit 7af11dcc42111aa6bd412a2410b2c42c17eb327b
Author: Yang Lu <yang@voltdb.com>
Date:   Tue Jul 8 11:47:47 2014 -0400

    For ENG-6482, as a flag of snapshot completion, create a .complete file
    when snapshot is finished.