Include reference to app user when creating a PM narrow
Include reference to app user when creating a PM narrow

Otherwise, a database search will show zero results.

Closes trac #2229.

abhaymaniyar/zulip-android,prati0100/zulip-android,saketkumar95/zulip-android,Sam1301/zulip-android,vishwesh3/zulip-android,saketkumar95/zulip-android,zulip/zulip-android,abhaymaniyar/zulip-android,Sam1301/zulip-android,prati0100/zulip-android