Change native content type checking logic

src/android/src/main/java/com/RNFetchBlob/RNFetchBlobBody.java

             String header = "--" + boundary + "\r\n";
             if (field.filename != null) {
                 header += "Content-Disposition: form-data; name=" + name + "; filename=" + field.filename + "\r\n";
-                header += "Content-Type: " + field.mime+ "\r\n\r\n";
+                header += "Content-Type: " + field.mime + "\r\n\r\n";
                 sink.write(header.getBytes());
                 // file field header end
                 // upload from storage

src/android/src/main/java/com/RNFetchBlob/RNFetchBlobReq.java

                         requestType = RequestType.SingleFile;
                     }
                     else if (cType.toLowerCase().contains(";base64") || cType.toLowerCase().startsWith("application/octet")) {
+                        cType = cType.replace(";base64","").replace(";BASE64","");
+                        if(mheaders.containsKey("content-type"))
+                            mheaders.put("content-type", cType);
+                        if(mheaders.containsKey("Content-Type"))
+                            mheaders.put("Content-Type", cType);
                         requestType = RequestType.SingleFile;
                     } else {
                         requestType = RequestType.AsIs;

src/ios/RNFetchBlobReqBuilder.m

                     // when content-type is application/octet* decode body string using BASE64 decoder
                     if([[cType lowercaseString] hasPrefix:@"application/octet"] || [[cType lowercaseString] containsString:@";base64"])
                     {
+                        __block NSString * ncType = [[cType stringByReplacingOccurrencesOfString:@";base64" withString:@""]stringByReplacingOccurrencesOfString:@";BASE64" withString:@""];
+                        if([mheaders valueForKey:@"content-type"] != nil)
+                            [mheaders setValue:ncType forKey:@"content-type"];
+                        if([mheaders valueForKey:@"Content-Type"] != nil)
+                            [mheaders setValue:ncType forKey:@"Content-Type"];
                         blobData = [[NSData alloc] initWithBase64EncodedString:body options:0];
                         [request setHTTPBody:blobData];
                         size = [blobData length];

src/polyfill/Fetch.js

         // When request body is a Blob, use file URI of the Blob as request body.
         else if (body.isRNFetchBlobPolyfill)
           promise = Promise.resolve(RNFetchBlob.wrap(body.blobPath))
+        else if (typeof body !== 'object')
+          promise = Promise.resolve(JSON.stringify(body))
+        else if (typeof body !== 'string')
+          promise = Promise.resolve(body.toString())
         // send it as-is, leave the native module decide how to send the body.
         else
           promise = Promise.resolve(body)