Fix upload signed certificate error through GUI

Noticed signed certificate uploaded fails certificate
validation.

Back-end appends the private key to the uploaded certificate
file and initiates certificate validation.

As end of line character is missing at the end of the uploaded
certificate private key is added on the same line.

Inserting end of line character before appending private key.

Tested:
1) Uplaoding signed certificate through GUI
2) Uploading signed certificate through command line

Change-Id: Iee944912a748a81e34ccad012707b925c451433e
Signed-off-by: Marri Devender Rao <devenrao@in.ibm.com>
diff --git a/certificate.cpp b/certificate.cpp
index b36e5f4..51c8ec6 100644
--- a/certificate.cpp
+++ b/certificate.cpp
@@ -468,6 +468,7 @@
         {
             privKeyFileStream.open(privateKeyFile);
             certFileStream.open(filePath, std::ios::app);
+            certFileStream << std::endl; // insert line break
             certFileStream << privKeyFileStream.rdbuf() << std::flush;
             privKeyFileStream.close();
             certFileStream.close();