Fix Python error in crypto.import_cert() (#262)

Patch to fix `import_cert()` method in crypto.py to handle
both python2 and python3 based methods

Fixes: https://pagure.io/dogtagpki/issue/3108

Signed-off-by: Dinesh Prasanth M K <dmoluguw@redhat.com>

base/common/python/pki/crypto.py

@@ -194,6 +194,9 @@ def import_cert(self, cert_nick, cert, trust=',,'):
         else:
             content = cert
 
+        if type(content) is not six.binary_type:
+            content = content.encode()
+
         # certutil -A -d db_dir -n cert_nick -t trust -i cert_file
         with tempfile.NamedTemporaryFile() as cert_file:
             cert_file.write(content)