Bump bignum version

S3 bucket for bignum 0.13.0 was hijacked
1 changed files with 1 additions and 1 deletions
--- a/package.json
+++ b/package.json
@ -30,7 +30,7 @@
    },
    "dependencies": {
        "async": "^2.6.3",
-        "bignum": "0.13.0",
+        "bignum": "0.13.1",
        "body-parser": "1.18.3",
        "colors": "1.3.2",
        "compression": "^1.7.4",