Fix vaadin plugin version

Author: snicoll

pom.xml

@@ -13,7 +13,6 @@
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
         <version.vaadin>7.7.3</version.vaadin>
-        <vaadin.plugin.version>${version.vaadin}</vaadin.plugin.version>
         <start-class>crud.Application</start-class>
     </properties>
 
@@ -85,6 +84,12 @@
             <scope>runtime</scope>
         </dependency>
 
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-devtools</artifactId>
+			<optional>true</optional>
+		</dependency>
+
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-test</artifactId>
@@ -114,7 +119,7 @@
             <plugin>
                 <groupId>com.vaadin</groupId>
                 <artifactId>vaadin-maven-plugin</artifactId>
-                <version>7.7.0</version>
+                <version>${version.vaadin}</version>
                 <executions>
                     <execution>
                         <goals>