Bump version to 0.15.2-alpha

Albums with tracks tagged with different years were showing one instance
of the album for each year present in the tracks. This should fix that.

Persephone.xcodeproj/project.pbxproj

@@ -1188,7 +1188,7 @@
 					"$(inherited)",
 					"$(PROJECT_DIR)/libmpdclient/output",
 				);
-				MARKETING_VERSION = "0.15.1-alpha";
+				MARKETING_VERSION = "0.15.2-alpha";
 				PRODUCT_BUNDLE_IDENTIFIER = me.danbarber.Persephone;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				PROVISIONING_PROFILE_SPECIFIER = "";
@@ -1217,7 +1217,7 @@
 					"$(inherited)",
 					"$(PROJECT_DIR)/libmpdclient/output",
 				);
-				MARKETING_VERSION = "0.15.1-alpha";
+				MARKETING_VERSION = "0.15.2-alpha";
 				PRODUCT_BUNDLE_IDENTIFIER = me.danbarber.Persephone;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				PROVISIONING_PROFILE_SPECIFIER = "";

Persephone/MPDClient/Models/MPDAlbum.swift

@@ -17,8 +17,7 @@ extension MPDClient {
 
     static func == (lhs: MPDAlbum, rhs: MPDAlbum) -> Bool {
       return lhs.title == rhs.title &&
-        lhs.artist == rhs.artist &&
-        lhs.date == rhs.date
+        lhs.artist == rhs.artist
     }
   }
 }