Added certificate revocation and CRL generation code.

.gitignore

@@ -6,7 +6,12 @@ lab-ca*
 *.pem
 # Ignore CA configuration and certificate definitions.
 *.hcl
+# Ignore state files
+*.json
 # Include example files
 !/examples/*.hcl
 # Exclude MacOS Finder metadata files
-.DS_Store
+.DS_Store
+# Exclude default certificate and private key files directories
+/certs/
+/private/