Refactoring of the Access Table

This commit does a lot of the work of refactoring the access table in a table with id's instead of strings.

The result does compile, but has not been tested. It may eat your kittens.

models/migrations/migrations.go

@@ -47,10 +47,11 @@ type Version struct {
 }
 
 // This is a sequence of migrations. Add new migrations to the bottom of the list.
-// If you want to "retire" a migration, remove it from the top of the list and 
-// update _MIN_VER_DB accordingly 
+// If you want to "retire" a migration, remove it from the top of the list and
+// update _MIN_VER_DB accordingly
 var migrations = []Migration{
 	NewMigration("generate collaboration from access", accessToCollaboration), // V0 -> V1
+	NewMigration("refactor access table to use id's", accessRefactor),         // V1 -> V2
 }
 
 // Migrate database to current version
@@ -206,3 +207,8 @@ func accessToCollaboration(x *xorm.Engine) error {
 
 	return sess.Commit()
 }
+
+func accessRefactor(x *xorm.Engine) error {
+	//TODO
+	return nil
+}