New video transcoder (#27)

* New video transcoder

* Set a smaller max muxing size + logging tweaks

* No need to return an err since it wiill panic anyway

* Use a default encoder preset if one is not supplied

* Rename to NewTranscoder.  Add comments.

* Rename Bitrate to VideoBitrate. Config file changes required with this rename.

* Allow overrides of segment length. Allow offline stream to live in a single segment

* Append offline state video to existin HLS stream instead of overwriting because players do not like that

* Make properties private as they do not need to be exported

core/playlist/writer.go

@@ -0,0 +1,18 @@
+package playlist
+
+import "os"
+
+//WritePlaylist writes the playlist to disk
+func WritePlaylist(data string, filePath string) error {
+	f, err := os.Create(filePath)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	if _, err := f.WriteString(data); err != nil {
+		return err
+	}
+
+	return nil
+}