jamiStrings: can't choose JPG as image

UpperCase extensions had to be added manually as Qt fileDialog's
nameFilters property is case sensitive.

GitLab: #832
Change-Id: I61a81ebcaa66f0f16db41924b542c146fc79a4b0

src/app/constant/JamiStrings.qml

@@ -584,7 +584,7 @@ Item {
     property string stopTakingPhoto: qsTr("Stop taking photo")
     property string clearAvatar: qsTr("Clear avatar image")
     property string takePhoto: qsTr("Take photo")
-    property string imageFiles: qsTr("Image Files (*.png *.jpg *.jpeg)")
+    property string imageFiles: qsTr("Image Files (*.png *.jpg *.jpeg *.JPG *.JPEG *.PNG)")
 
     // Plugins
     property string enable: qsTr("Enable")