(VDB-298) Consume Pit contract storage diffs

- Continuously parse storage diffs CSV data to read Pit contract state
- Convert ilks in database to raw bytes32 value for use in generating
  storage keys dynamically
- Persist storage diffs with block number and hash for validation

pkg/fs/reader.go

@@ -22,8 +22,7 @@ type Reader interface {
 	Read(path string) ([]byte, error)
 }
 
-type FsReader struct {
-}
+type FsReader struct{}
 
 func (FsReader) Read(path string) ([]byte, error) {
 	return ioutil.ReadFile(path)

pkg/fs/tail.go

@@ -0,0 +1,15 @@
+package fs
+
+import "github.com/hpcloud/tail"
+
+type Tailer interface {
+	Tail() (*tail.Tail, error)
+}
+
+type FileTailer struct {
+	Path string
+}
+
+func (tailer FileTailer) Tail() (*tail.Tail, error) {
+	return tail.TailFile(tailer.Path, tail.Config{Follow: true})
+}