How can I change Xcode capabilities when I use Jenkins?

Question

I have a Unity project and I want to enable push notifications in the Xcode project. I use Unity 4.6.2p4 and Xcode 8.3.3

enter image description here

I tried a couple of things. First, I used the pbxproj library in PostBuildProcess in the Unity script. But I couldn't change the capabilities. Here is the code:

project = new PBXProject()
project.AddBuildProperty(target, "SystemCapabilities", "{com.apple.Push = {enabled = 1;};}");

Second, I copied the settings pbxproj. I did this because I read in an article that pbxproj file affects the capabilities. But it is not working.

I read that the entitlements file can affect capabilities as well. But I can't understand where it is and how I can edit it. How can I set push notifications in Xcode? Please consider I'm not very familiar with Xcode's project file structure.