Merge #234: remove the lockfile if sup isn't already launched

Fixes #233.

Squashed commit of the following:

commit 5dd0ffec3d2aba071c02816298ad6801d690e4ae
Author: julien@macbook <julien.stechele@gmail.com>
Date:   Mon Feb 24 12:53:11 2014 +0100

    Sleep a couple of seconds before locking one more time

commit 235aff8327d8f2df8d41febbdabb481f5bd8fc9f
Author: julien@macbook <julien.stechele@gmail.com>
Date:   Mon Feb 24 12:42:04 2014 +0100

    true need a return like false

commit bf0cc9bb9e8c137be50c29a85f5ccc44b899085e
Author: julien@macbook <julien.stechele@gmail.com>
Date:   Wed Feb 19 16:21:38 2014 +0100

    false alone has no effect, use return with

commit 09f1034bc51ec6843f61f16db1ec2bd85cefc8d0
Author: julien@macbook <julien.stechele@gmail.com>
Date:   Wed Feb 19 16:20:04 2014 +0100

    Message + false

commit 58a0248486373fe26c53cc094b13ec050c982f6b
Author: julien@macbook <julien.stechele@gmail.com>
Date:   Wed Feb 19 16:15:06 2014 +0100

    Fix indentation

commit 072531a3e2d16bde21afb53b630f3c4f9031122a
Author: julien@macbook <julien.stechele@gmail.com>
Date:   Mon Feb 17 16:28:56 2014 +0100

    issue-233: remove the lockfile if sup isn't already launched