fixed bug for setValue in refreshAccessToken
fixed bug for setValue in refreshAccessToken

Since OCRepresentation doesn't perceive a const string as std::string value,
need to clarify a type of parameter.
Otherwise, it is passed as a true boolean value whatever it is.

Change-Id: I3db677f6bdf59bf23036dc678781b35af95025e6
Signed-off-by: Jaewook Jung <e30c770b7f9b30402e4d6c2240cd5b03cb3bf7f9@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/10539
Tested-by: jenkins-iotivity <09cb29e8a2b473a2c978382eec13ee06fa017bda@opendaylight.org>
Reviewed-by: Jee Hyeok Kim <ecfb86b5d85d5430a7602d1e11f4f25d16714d36@samsung.com>

iotivity/iotivity,iotivity/iotivity,rzr/iotivity,rzr/iotivity,rzr/iotivity,rzr/iotivity,iotivity/iotivity,iotivity/iotivity,iotivity/iotivity,iotivity/iotivity,rzr/iotivity,iotivity/iotivity,iotivity/iotivity,rzr/iotivity,rzr/iotivity