Web API poll display item only follows web api calls not UI actions

[Simon Goodfellow]

Web API poll display item only follows web api calls and ignores UI actions. It would help if the initial state was "true" to match the desktop display at that point.

Recreate
1. Run OpenLP
../api/poll
{"results": {"item": "", "slide": 0, "twelve": true, "service": 0, "display": false, "blank": false, "isSecure": false, "isAuthorised": true, "version": 2, "theme": false}}
****would be good if display=true matching the desktop state
2. Go Live on a service item
../api/poll
{"results": {"item": "9f519ea0-0674-11e7-881b-080027182b31", "slide": 0, "twelve": true, "service": 1, "display": false, "blank": false, "isSecure": false, "isAuthorised": true, "version": 2, "theme": false}}
****display still false but now it is correct
3. Use keyboard ESC to go back to the desktop
../api/poll
4. {"results": {"item": "9f519ea0-0674-11e7-881b-080027182b31", "slide": 0, "twelve": true, "service": 1, "display": false, "blank": false, "isSecure": false, "isAuthorised": true, "version": 2, "theme": false}}
****display still false, should be true
4. …/api/display/show
../api/poll
{"results": {"item": "9f519ea0-0674-11e7-881b-080027182b31", "slide": 0, "twelve": true, "service": 1, "display": false, "blank": false, "isSecure": false, "isAuthorised": true, "version": 2, "theme": false}}
**** display still false but now correct
5. …/api/display/desktop
../api/poll
{"results": {"item": "9f519ea0-0674-11e7-881b-080027182b31", "slide": 0, "twelve": true, "service": 1, "display": true, "blank": false, "isSecure": false, "isAuthorised": true, "version": 2, "theme": false}}
*** display=true it tracks changes from web API only.