[Websetting] Explicit call picosjon::value constructor

[Websetting] Explicit call picosjon::value constructor

[Problem]
On TV I can't call 'std::map<std::basic_string<char>, picojson::value>::insert(std::pair<const char*, [other type]>)
I must use explicit conversion.
This error occurs probably because there is different version of gcc for mobile and TV

[Solution]
I used explicit picosjon::value constructor

[Verification]
Code complies without errors

Signed-off-by: Mariusz Polasinski <m.polasinski@samsung.com>
Change-Id: I06aaf19636839e0d851f0ba05a0ae6b4a254b357