Add starter, make adapter kick in only if needed

spring-shell-jcommander-adapter/pom.xml

@@ -23,6 +23,7 @@
 			<groupId>com.beust</groupId>
 			<artifactId>jcommander</artifactId>
 			<version>1.48</version>
+			<optional>true</optional>
 		</dependency>
 		<dependency>
 			<groupId>org.springframework.boot</groupId>