Move rand pin to 0.6

Fixes #57

Author: ramosbugs

Cargo.toml

@@ -11,7 +11,7 @@ base64 = "0.9"
 curl = "0.4.0"
 failure = "0.1"
 failure_derive = "0.1"
-rand = "0.4"
+rand = "0.6"
 serde = "1.0"
 serde_json = "1.0"
 serde_derive = "1.0"