Allow json and yaml for file backend

[andrewheberle]

This PR adds a check in the file backend and performs a YAML or JSON unmarshal depending on the file extension

[abtreece]

Hey @andrewheberle

It appears that the import should be path/filepath

index 6ee8fa4..24f0620 100644
--- a/backends/file/client.go
+++ b/backends/file/client.go
@@ -2,7 +2,7 @@ package file

 import (
        "encoding/json"
-       "filepath"
+       "path/filepath"
        "fmt"
        "io/ioutil"
        "path"

Also, can you add integration tests for .json files... integration/file/test.sh

[andrewheberle]

I've fixed that error and added the tests, which uncovered a problem with the original code, so there are a few more changes in backends/file/client.go