Queue meta data (#121)

* Added migrations

Added new table to store metadata

* Updated table

* Added code for new endpoint

* Updated module

* Code formatting:

* Added test code

* Fixed test

* Cleanup

* Code refactor

src/callers/mod.rs

@@ -1,5 +1,7 @@
+pub mod metadata;
 pub mod song;
 
 pub mod endpoints {
     pub const QUEUESONG: &str = "/api/v2/song/queue";
+    pub const QUEUEMETADATA: &str = "/api/v2/song/metadata/queue";
 }