Command Line Interface to Run Games Locally (#25)

* Initial Attempts at Cobra Command
* Update to the README
* Fixes for Linter

Thanks @LenPayne for all your hard work getting this started!

cli/main.go

@@ -0,0 +1,7 @@
+package main
+
+import "github.com/BattlesnakeOfficial/rules/cli/cmd"
+
+func main() {
+	cmd.Execute()
+}