[messaging][bugfix] Don't convert filter's matchValue to String

[messaging][bugfix] Don't convert filter's matchValue to String

Due to a conversion of matchValue to String, filters with boolean
matchValues did not match objects.

[Verification] All subtest cases, dealing with boolean attributes,
introduced in TCT in commit
https://review.tizen.org/gerrit/#/c/test/tct/web/api/+/199159/
passed.

This commit has already been reviewed:
https://review.tizen.org/gerrit/#/c/platform/core/api/webapi-plugins/+/200661/
Change-Id of the original change was:
I72fc83328e92529455460469c5dbc1aadc6ce07e

Signed-off-by: Pawel Wasowski <p.wasowski2@samsung.com>
Change-Id: Ia8d769b1a9694defdcb403761cff9c2565f5f52b