Add spring.thymeleaf.contentType (defaults to HTML)

User can specify the content type in external properties now, optionally
ommitting the charset (since that is duplicated). If charset is not
appended by user Spring will do it.

Fixes gh-671

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/thymeleaf/ThymeleafAutoConfiguration.java

@@ -178,6 +178,9 @@ public class ThymeleafAutoConfiguration {
 			resolver.setTemplateEngine(this.templateEngine);
 			resolver.setCharacterEncoding(this.environment.getProperty("encoding",
 					"UTF-8"));
+			resolver.setContentType(addEncoding(
+					this.environment.getProperty("contentType", "text/html"),
+					resolver.getCharacterEncoding()));
 			resolver.setExcludedViewNames(this.environment.getProperty(
 					"excludedViewNames", String[].class));
 			resolver.setViewNames(this.environment.getProperty("viewNames",
@@ -188,6 +191,15 @@ public class ThymeleafAutoConfiguration {
 			return resolver;
 		}
 
+		private String addEncoding(String type, String charset) {
+			if (type.contains("charset=")) {
+				return type;
+			}
+			else {
+				return type + ";charset=" + charset;
+			}
+		}
+
 	}
 
 	@Configuration

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/thymeleaf/ThymeleafAutoConfigurationTests.java

@@ -84,6 +84,7 @@ public class ThymeleafAutoConfigurationTests {
 		assertEquals("UTF-16", ((TemplateResolver) resolver).getCharacterEncoding());
 		ThymeleafViewResolver views = this.context.getBean(ThymeleafViewResolver.class);
 		assertEquals("UTF-16", views.getCharacterEncoding());
+		assertEquals("text/html;charset=UTF-16", views.getContentType());
 	}
 
 	@Test