Update snapshot dependency in maven sample projects

Change-Id: I1078b0f7d0d5bfad4c3bae924a760a61e5272f30
diff --git a/samples/dynatablerf/pom.xml b/samples/dynatablerf/pom.xml
index ad250d5..6a171a0 100644
--- a/samples/dynatablerf/pom.xml
+++ b/samples/dynatablerf/pom.xml
@@ -13,7 +13,7 @@
 
   <properties>
     <!-- Convenience property to set the GWT version -->
-    <gwt.version>2.8.0-SNAPSHOT</gwt.version>
+    <gwt.version>HEAD-SNAPSHOT</gwt.version>
 
     <!-- Setting maven.compiler.source to something different to 1.8
          needs that you configure the sourceLevel in gwt-maven-plugin since
diff --git a/samples/mobilewebapp/pom.xml b/samples/mobilewebapp/pom.xml
index 81bc407..faa531a 100644
--- a/samples/mobilewebapp/pom.xml
+++ b/samples/mobilewebapp/pom.xml
@@ -11,7 +11,7 @@
 
   <properties>
     <!-- Convenience property to set the GWT version -->
-    <gwt.version>2.8.0-SNAPSHOT</gwt.version>
+    <gwt.version>HEAD-SNAPSHOT</gwt.version>
 
     <!-- Setting maven.compiler.source to something different to 1.8
          needs that you configure the sourceLevel in gwt-maven-plugin since
diff --git a/samples/validation/pom.xml b/samples/validation/pom.xml
index e050657..fb72eca 100644
--- a/samples/validation/pom.xml
+++ b/samples/validation/pom.xml
@@ -11,7 +11,7 @@
 
   <properties>
     <!-- Convenience property to set the GWT version -->
-    <gwt.version>2.8.0-SNAPSHOT</gwt.version>
+    <gwt.version>HEAD-SNAPSHOT</gwt.version>
 
     <!-- Setting maven.compiler.source to something different to 1.8
          needs that you configure the sourceLevel in gwt-maven-plugin since