Add build.gradle samples and rename runJar->bootRun

spring-boot-samples/spring-boot-sample-simple/README.md

@@ -0,0 +1,19 @@
+# Spring Boot Simple Sample
+
+You can build this sample using Maven (>3) or Gradle (1.6). 
+
+With Maven:
+
+```
+$ mvn package
+$ java -jar target/*.jar
+```
+
+The app prints a Hello message on the console.
+
+With gradle:
+
+```
+$ gradle build
+$ java -jar build/libs/*.jar
+```