Store group details in the database. Some tests are still failing...

api/net/sf/briar/api/db/DatabaseComponent.java

api/net/sf/briar/api/protocol/Group.java

api/net/sf/briar/api/protocol/GroupFactory.java

api/net/sf/briar/api/protocol/SubscriptionWriter.java

api/net/sf/briar/api/protocol/Subscriptions.java

components/net/sf/briar/crypto/CryptoModule.java

components/net/sf/briar/crypto/KeyParserImpl.java

components/net/sf/briar/db/Database.java

components/net/sf/briar/db/H2Database.java

components/net/sf/briar/db/JdbcDatabase.java

...nents/net/sf/briar/db/ReadWriteLockDatabaseComponent.java

...onents/net/sf/briar/db/SynchronizedDatabaseComponent.java

components/net/sf/briar/protocol/GroupFactoryImpl.java

components/net/sf/briar/protocol/GroupImpl.java

components/net/sf/briar/protocol/ProtocolModule.java

test/net/sf/briar/db/DatabaseComponentTest.java

test/net/sf/briar/db/H2DatabaseTest.java

test/net/sf/briar/protocol/BatchReaderTest.java

test/net/sf/briar/protocol/ConsumersTest.java

test/net/sf/briar/protocol/FileReadWriteTest.java