Merge tag '1.2.0' into develop

- Added File field type for the new Field component introduced in Cog 3.1.0
- Added a task that will check the files directory for any files not known in the database and add them to the file manager database. Handy for porting in a large amount of files
- Fixed bug where it was not possible to serialize the `File` model object
- Fixed issues where images files would not display after being serialised and unserialised (#64)

composer.json

@@ -29,7 +29,7 @@
 	"require": {
 		"php": ">=5.4.0",
 
-		"message/cog"              : "~3.0",
+		"message/cog"              : "~3.1",
 		"message/cog-imageresize"  : "~1.0",
 		"message/cog-mothership-cp": "~1.1"
 	},