Install asn1crypto automatically if not present

scripts/preBuildCertificates.py

@@ -4,7 +4,15 @@
 import re
 import string
 import sys
-from asn1crypto.x509 import Certificate
+try:
+    from asn1crypto.x509 import Certificate
+except ImportError:
+    env.Execute(
+        env.VerboseAction(
+            '$PYTHONEXE -m pip install "asn1crypto" ',
+            "ASN1 crypto import failed, installing.",
+        )
+    )
 import hashlib
 
 from subprocess import Popen, PIPE, call, check_output
@@ -182,4 +190,4 @@ def preBuildCertificatesFun(domains):
             f.write(", ")
     f.write("};\n\n#endif" + "\n")
 
-    f.close()
+    f.close()