Packaging|ubuntu, issue #601: Allow packaging prerm to do its job
Merge pull request #1099 from lopter/master

*Test :  Fix
add sleep in tests and go fmt
Merge pull request #1101 from dotcloud/fix-unit_tests

add sleep in tests and go fmt
Merge pull request #987 from dotcloud/601-packaging-ubuntu

Packaging|ubuntu, issue #601: Allow packaging prerm to do its job
When no tag is specified in docker pull, skip images that are not tagged
Merge pull request #1103 from shin-/1060-pull-only-tagged-images

*Registry: When no tag is specified in docker pull, skip images that are not tagged