Suppress warnings related to missing CA cert files.

Per #887

Author: tresf

src/qz/installer/Installer.java

@@ -208,11 +208,15 @@ public CertificateManager certGen(boolean forceNew, String... hostNames) throws
                 FirefoxCertificateInstaller.install(caCert, hostNames);
             } else {
                 // Make sure the certificate is recognized by the system
-                File tempCert = File.createTempFile(KeyPairWrapper.getAlias(KeyPairWrapper.Type.CA) + "-", CertificateManager.DEFAULT_CERTIFICATE_EXTENSION);
-                CertificateManager.writeCert(caCert, tempCert); // temp cert
-                if(!installer.verify(tempCert)) {
-                    installer.install(caCert);
-                    FirefoxCertificateInstaller.install(caCert, hostNames);
+                if(caCert == null) {
+                    log.info("CA cert is empty, skipping installation checks.  This is normal for trusted/3rd-party SSL certificates.");
+                } else {
+                    File tempCert = File.createTempFile(KeyPairWrapper.getAlias(KeyPairWrapper.Type.CA) + "-", CertificateManager.DEFAULT_CERTIFICATE_EXTENSION);
+                    CertificateManager.writeCert(caCert, tempCert); // temp cert
+                    if (!installer.verify(tempCert)) {
+                        installer.install(caCert);
+                        FirefoxCertificateInstaller.install(caCert, hostNames);
+                    }
                 }
             }
         }

src/qz/ws/PrintSocketServer.java

@@ -36,6 +36,7 @@
 import javax.swing.*;
 import java.io.File;
 import java.io.IOException;
+import java.security.cert.X509Certificate;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
@@ -97,7 +98,11 @@ public static void main(String[] args) {
 
         // Linux needs the cert installed in user-space on every launch for Chrome SSL to work
         if (!SystemUtilities.isWindows() && !SystemUtilities.isMac()) {
-            NativeCertificateInstaller.getInstance().install(certificateManager.getKeyPair(KeyPairWrapper.Type.CA).getCert());
+            X509Certificate caCert = certificateManager.getKeyPair(KeyPairWrapper.Type.CA).getCert();
+            // Only install if a CA cert exists (e.g. one we generated)
+            if(caCert != null) {
+                NativeCertificateInstaller.getInstance().install(certificateManager.getKeyPair(KeyPairWrapper.Type.CA).getCert());
+            }
         }
 
         try {