Performed refactoring and code cleanup on service provider plug-in.

Performed refactoring and code cleanup on service provider plug-in.

1. Removed unnecessary data duplication.
2. Combined together all image/icon related code into a single ImageManager class.
3. Removed unnecessary console log.

Change-Id: Iaa9e8b319cdff13468b230aa6fe46f490264bc90
Signed-off-by: G S Senthil Kumar <senthil.gs@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/2379
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Madan Lanka <lanka.madan@samsung.com>