Refactoring to batch (#181)

The rationale of this pull request is to

* have more maintainable and granular code
* not maintain the custom made job engine
* allow the users to customize the defaults of the releaser more easy
* allow the users to create their own steps without the need to change any existing code
* allow the users to fully change the flows and tasks logic
* abstract underlying batch mechanism (Spring Batch) so it doesn't leak to production code
* allow parallelization of the release process and release tasks

projects/spring-cloud-stream/src/test/java/releaser/ReleaserApplicationTests.java

@@ -0,0 +1,59 @@
+/*
+ * Copyright 2013-2019 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
+ *
+ *      https://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 releaser;
+
+import org.junit.jupiter.api.Test;
+import org.mockito.Mockito;
+import releaser.internal.options.Parser;
+import releaser.internal.spring.ExecutionResultHandler;
+import releaser.internal.spring.SpringReleaser;
+
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+@SpringBootTest(
+		classes = { ReleaserApplicationTests.Config.class, ReleaserApplication.class },
+		properties = { "releaser.sagan.update-sagan=false" })
+class ReleaserApplicationTests {
+
+	@Test
+	void contextLoads() {
+
+	}
+
+	@Configuration
+	static class Config {
+
+		@Bean
+		SpringReleaser mockReleaser() {
+			return Mockito.mock(SpringReleaser.class);
+		}
+
+		@Bean
+		ExecutionResultHandler mockExecutionResultHandler() {
+			return Mockito.mock(ExecutionResultHandler.class);
+		}
+
+		@Bean
+		Parser mockParser() {
+			return Mockito.mock(Parser.class);
+		}
+
+	}
+
+}