Make numbers always quoted (#37)

Author: dawon

src/main/kotlin/net/minecrell/pluginyml/GeneratePluginDescription.kt

@@ -69,6 +69,7 @@ abstract class GeneratePluginDescription : DefaultTask() {
         val factory = YAMLFactory()
             .disable(YAMLGenerator.Feature.WRITE_DOC_START_MARKER)
             .enable(YAMLGenerator.Feature.MINIMIZE_QUOTES)
+            .enable(YAMLGenerator.Feature.ALWAYS_QUOTE_NUMBERS_AS_STRINGS)
 
         val module = SimpleModule()
         @Suppress("UNCHECKED_CAST") // Too stupid to figure out the generics here...