Add JdbcOperationsSessionRepository

This commit provides implementation of SessionRepository based
on Spring's JdbcOperations interface.

@EnableJdbcHttpSession annotation is provided to ease the
configuration, together with spring-session-jdbc BOM and schema
creation scripts for all major databases.

Fixes gh-364

samples/httpsession-jdbc/src/main/java/sample/Config.java

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2014-2016 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package sample;
+
+import javax.sql.DataSource;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.jdbc.datasource.DataSourceTransactionManager;
+import org.springframework.jdbc.datasource.embedded.EmbeddedDatabase;
+import org.springframework.jdbc.datasource.embedded.EmbeddedDatabaseBuilder;
+import org.springframework.jdbc.datasource.embedded.EmbeddedDatabaseType;
+import org.springframework.session.jdbc.config.annotation.web.http.EnableJdbcHttpSession;
+import org.springframework.transaction.PlatformTransactionManager;
+
+// tag::class[]
+@EnableJdbcHttpSession // <1>
+public class Config {
+
+	@Bean
+	public EmbeddedDatabase dataSource() {
+		return new EmbeddedDatabaseBuilder() // <2>
+				.setType(EmbeddedDatabaseType.H2)
+				.addScript("org/springframework/session/jdbc/schema-h2.sql")
+				.build();
+	}
+
+	@Bean
+	public PlatformTransactionManager transactionManager(DataSource dataSource) {
+		return new DataSourceTransactionManager(dataSource); // <3>
+	}
+
+}
+// end::class[]