Add support for multipart/mixed content type

.gitattributes

@@ -0,0 +1 @@
+*.http	-text

index.js

@@ -39,7 +39,7 @@ var COLON = 58;
 var A = 97;
 var Z = 122;
 
-var CONTENT_TYPE_RE = /^multipart\/(?:form-data|related)(?:;|$)/i;
+var CONTENT_TYPE_RE = /^multipart\/(?:form-data|related|mixed)(?:;|$)/i;
 var CONTENT_TYPE_PARAM_RE = /;\s*([^=]+)=(?:"([^"]+)"|([^;]+))/gi;
 var FILE_EXT_RE = /(\.[_\-a-zA-Z0-9]{0,16}).*/;
 var LAST_BOUNDARY_SUFFIX_LEN = 4; // --\r\n

test/fixture/http/content-type/multipart-mixed.http

@@ -0,0 +1,13 @@
+POST /upload HTTP/1.1
+Host: localhost:8080
+Content-Type: multipart/form-data; custom=stuff; boundary=----TLV0SrKD4z1TRxRhAPUvZ
+Content-Length: 213
+
+------TLV0SrKD4z1TRxRhAPUvZ
+Content-Disposition: form-data; name="file"; filename="plain.txt"
+Content-Type: text/plain
+Content-Transfer-Encoding: 7bit
+
+I am a plain text file
+
+------TLV0SrKD4z1TRxRhAPUvZ--

test/fixture/js/content-type.js

@@ -42,3 +42,14 @@ module.exports['custom-equal-sign.http'] = [
     size: 24,
   }
 ];
+
+module.exports['multipart-mixed.http'] = [
+  {
+    type: 'file',
+    name: 'file',
+    filename: 'plain.txt',
+    fixture: 'plain.txt',
+    sha1: 'b31d07bac24ac32734de88b3687dddb10e976872',
+    size: 23,
+  }
+];