Add symbols for mime_types to the default config

conf/metrics.conf

@@ -1201,4 +1201,26 @@ metric {
     		description = "DMARC failed";
     	}
     }
+    group {
+    	name = "mime_types";
+
+    	symbol {
+    		weight = -0.1;
+    		name = "MIME_GOOD";
+    		description = "Known content-type";
+			one_shot = true;
+    	}
+    	symbol {
+    		weight = 1.0;
+    		name = "MIME_BAD";
+    		description = "Known bad content-type";
+			one_shot = true;
+    	}
+    	symbol {
+    		weight = 0.1;
+    		name = "MIME_UNKNOWN";
+    		description = "Missing or unknown content-type";
+			one_shot = true;
+    	}
+    }
 }

conf/modules.d/mime_types.conf

@@ -0,0 +1,4 @@
+mime_types {
+    .include(try=true,priority=1) "${DBDIR}/dynamic/mime_types.conf"
+    file = "${ETCDIR}/mime_types.inc";
+}