Avoid user wavelets for anonymous users

[pablojan]

Avoid generating user's wavelet for anoymous users in order to not overload wave loading.
Each time a wave is loaded from storage, a new wavelet must be loaded in memory for each user.
In public waves, there could be a lot of anonymous users, and situation can become critical

Following example shows a wave being loaded from persistence, each user wavelet takes about 30-40ms...

NFO: Snapshot loaded for demo.swellrt.org/maldivas2016/swl+root in 31ms
Oct 18, 2016 4:38:52 PM org.waveprotocol.box.server.waveserver.DeltaStoreBasedWaveletState create
INFO: Snapshot built for demo.swellrt.org/maldivas2016/[email protected] in 36ms
Oct 18, 2016 4:38:52 PM org.waveprotocol.box.server.waveserver.DeltaStoreBasedWaveletState create
INFO: Snapshot built for demo.swellrt.org/maldivas2016/[email protected] in 37ms
Oct 18, 2016 4:38:52 PM org.waveprotocol.box.server.waveserver.DeltaStoreBasedWaveletState create
INFO: Snapshot built for demo.swellrt.org/maldivas2016/[email protected] in 37ms
Oct 18, 2016 4:38:52 PM org.waveprotocol.box.server.waveserver.DeltaStoreBasedWaveletState create
INFO: Snapshot built for demo.swellrt.org/maldivas2016/[email protected] in 38ms
Oct 18, 2016 4:38:52 PM org.waveprotocol.box.server.waveserver.DeltaStoreBasedWaveletState create
INFO: Snapshot built for demo.swellrt.org/maldivas2016/[email protected] in 42ms
Oct 18, 2016 4:38:52 PM org.waveprotocol.box.server.waveserver.DeltaStoreBasedWaveletState create
INFO: Snapshot built for demo.swellrt.org/maldivas2016/[email protected] in 36ms
Oct 18, 2016 4:38:52 PM org.waveprotocol.box.server.waveserver.DeltaStoreBasedWaveletState create
INFO: Snapshot built for demo.swellrt.org/maldivas2016/[email protected] in 36ms
Oct 18, 2016 4:38:52 PM org.waveprotocol.box.server.waveserver.DeltaStoreBasedWaveletState create
INFO: Snapshot built for demo.swellrt.org/maldivas2016/[email protected] in 36ms
Oct 18, 2016 4:38:52 PM org.waveprotocol.box.server.waveserver.DeltaStoreBasedWaveletState create
INFO: Snapshot built for demo.swellrt.org/maldivas2016/[email protected] in 40ms
Oct 18, 2016 4:38:52 PM org.waveprotocol.box.server.waveserver.DeltaStoreBasedWaveletState create
INFO: Snapshot built for demo.swellrt.org/maldivas2016/[email protected] in 37ms
Oct 18, 2016 4:38:52 PM org.waveprotocol.box.server.waveserver.DeltaStoreBasedWaveletState create
INFO: Snapshot built for demo.swellrt.org/maldivas2016/[email protected] in 37ms
Oct 18, 2016 4:38:52 PM org.waveprotocol.box.server.waveserver.DeltaStoreBasedWaveletState create
INFO: Snapshot built for demo.swellrt.org/maldivas2016/[email protected] in 36ms
Oct 18, 2016 4:38:52 PM org.waveprotocol.box.server.waveserver.DeltaStoreBasedWaveletState create
INFO: Snapshot built for demo.swellrt.org/maldivas2016/[email protected] in 36m