I know Android 5.0 supports BLE peripheral mode, but i am not so sure if it works on Nexus 4 with Android 5.0.
The QuickBeacon app is not compatible with Nexus 4, which is suspicious.
BLE peripheral mode only works on Nexus 6/9 but not older Nexus devices.
Someone from Google explained the situation in comment #52 of the following issue in AOSP https://code.google.com/p/android-developer-preview/issues/detail?id=1570