Added liquibase autoconfiguration for database migrations

If Liquibase is on the classpath it will fire up on startup. Various
config options are available (as well as the option to disable it).
Liquibase uses a YAML format for changes (in classpath:db/changelog).

spring-boot-samples/spring-boot-sample-liquibase/src/test/java/sample/liquibase/SampleLiquibaseApplicationTests.java

@@ -0,0 +1,66 @@
+/*
+ * Copyright 2012-2014 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.liquibase;
+
+import java.net.ConnectException;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.springframework.boot.test.OutputCapture;
+import org.springframework.core.NestedCheckedException;
+
+import static org.junit.Assert.assertTrue;
+
+public class SampleLiquibaseApplicationTests {
+
+	@Rule
+	public OutputCapture outputCapture = new OutputCapture();
+
+	@Test
+	public void testDefaultSettings() throws Exception {
+		try {
+			SampleLiquibaseApplication.main(new String[0]);
+		}
+		catch (IllegalStateException ex) {
+			if (serverNotRunning(ex)) {
+				return;
+			}
+		}
+		String output = this.outputCapture.toString();
+		assertTrue("Wrong output: " + output,
+				output.contains("Successfully acquired change log lock") &&
+				output.contains("Creating database history table with name: PUBLIC.DATABASECHANGELOG") &&
+				output.contains("Table person created") &&
+				output.contains("ChangeSet classpath:/db/changelog/db.changelog-master.yaml::1::marceloverdijk ran successfully") &&
+				output.contains("New row inserted into person") &&
+				output.contains("ChangeSet classpath:/db/changelog/db.changelog-master.yaml::2::marceloverdijk ran successfully") &&
+				output.contains("Successfully released change log lock"));
+	}
+
+	private boolean serverNotRunning(IllegalStateException ex) {
+		@SuppressWarnings("serial")
+		NestedCheckedException nested = new NestedCheckedException("failed", ex) {
+		};
+		if (nested.contains(ConnectException.class)) {
+			Throwable root = nested.getRootCause();
+			if (root.getMessage().contains("Connection refused")) {
+				return true;
+			}
+		}
+		return false;
+	}
+}