Issues/25

[pjonckiere]

• config is handled by config management in core (AddThisSettingsForm & AddThisSettingsFormAdvanced)
• the json object was just initialized, thus shouldn’t be stored as a variable
• getServices() and getServicesJsonUrl() should live in a service
• fixed some docblocks
• check_url() is deprecated, so replaced by Html::escape(UrlHelper::stripDangerousProtocols($uri))
• the AddThis class has no use anymore so can be safely removed
• in AddThisSettingForm, the $configFactory is stored on it’s parent so there is no need to save another variable with that value