Upgrade Cats and Circe Version

```
libraryDependencies += "org.typelevel" %% "cats" % "0.7.2"
```

and 

```
val circeVersion = "0.5.2"

libraryDependencies ++= Seq(
  "io.circe" %% "circe-core",
  "io.circe" %% "circe-generic",
  "io.circe" %% "circe-parser"
).map(_ % circeVersion)
```
