Replace utils.dumps with jsonutils.dumps

In one of the previous patchsets which addresses Bug#1365263
(Idc5ee0fec56b0a0f337433a830647d4f421a8283) utils.dumps was replaced with
jsonutils.dumps. This patch addresses the changes in the remaining files.

Change-Id: Ie8c28d8cd2006e520d1a10ac26111886f63e12da
Closes-bug: 1368835
Merge "Replace utils.dumps with jsonutils.dumps"