MyIdentityPage: Fix Db4oException

Symptom would be the following exception upon accessing the page on the
web interface:

com.db4o.ext.Db4oException: This constraint is not persistent. It has no
database identity.
	at
com.db4o.internal.Exceptions4.throwRuntimeException(Exceptions4.java:54)
	at
com.db4o.internal.Exceptions4.throwRuntimeException(Exceptions4.java:44)
	at
com.db4o.internal.Exceptions4.throwRuntimeException(Exceptions4.java:32)
	at
com.db4o.internal.query.processor.QConObject.identity(QConObject.java:426)
	at
plugins.WebOfTrust.WebOfTrust.getReceivedTrusts(WebOfTrust.java:2444)
	at plugins.WebOfTrust.ui.web.MyIdentityPage.(MyIdentityPage.java:55)
	at
plugins.WebOfTrust.ui.web.WebInterface$MyIdentityWebInterfaceToadlet.makeWebPage(WebInterface.java:114)
	at
plugins.WebOfTrust.ui.web.WebInterfaceToadlet.handleRequest(WebInterfaceToadlet.java:199)
	at
plugins.WebOfTrust.ui.web.WebInterfaceToadlet.handleMethodGET(WebInterfaceToadlet.java:152)
	at
freenet.clients.http.ToadletContextImpl.callToadletMethod(ToadletContextImpl.java:711)
	at
freenet.clients.http.ToadletContextImpl.handle(ToadletContextImpl.java:648)
	at
freenet.clients.http.SimpleToadletServer$SocketHandler.run(SimpleToadletServer.java:1031)
	at
freenet.support.PooledExecutor$MyThread.innerRun(PooledExecutor.java:248)
	at
freenet.support.PooledExecutor$MyThread.realRun(PooledExecutor.java:188)
	at freenet.support.io.NativeThread.run(NativeThread.java:129)