Fix error message for java home missing (#174)

* Fix error message for java home missing

* match text to other shell scripts for JAVA_HOME

Author: jshum2479

imagetool/src/main/bin/imagetool.cmd

@@ -6,7 +6,7 @@
 @rem Licensed under the Universal Permissive License v 1.0 as shown at https://oss.oracle.com/licenses/upl.
 
 IF "%JAVA_HOME%" == "" (
-  ECHO JAVA_HOME not set. Please set JAVA_HOME to jdk home. OpenJDK is not supported.
+  ECHO Please set the JAVA_HOME environment variable to match the location of your Java installation. Java 8 or newer is required.
   EXIT /B 2
 )
 FOR %%i IN ("%JAVA_HOME%") DO SET JAVA_HOME=%%~fsi
@@ -18,4 +18,4 @@ IF EXIST %JAVA_HOME%\bin\java.exe (
   EXIT /B 2
 )
 SET IMAGETOOL_HOME=%~dp0%/..
-%JAVA_HOME%\bin\java -cp %IMAGETOOL_HOME%\lib\* -Djava.util.logging.config.file=%IMAGETOOL_HOME%\bin\logging.properties com.oracle.weblogic.imagetool.cli.ImageTool %*
+%JAVA_HOME%\bin\java -cp %IMAGETOOL_HOME%\lib\* -Djava.util.logging.config.file=%IMAGETOOL_HOME%\bin\logging.properties com.oracle.weblogic.imagetool.cli.ImageTool %*