added saveImage with extension

.../ardublock/translator/block/code/CommentProgramBlock.java

src/main/java/com/ardublock/ui/OpenblocksFrame.java

...com/ardublock/ui/listener/GenerateCodeButtonListener.java

...va/com/ardublock/ui/listener/SaveImageButtonListener.java

...com/ardublock/ui/listener/SimulateCodeButtonListener.java

src/main/resources/com/ardublock/block/ardublock.properties

...ain/resources/com/ardublock/block/ardublock_de.properties