Add initial implementation of grants

internal/models/grant.go

@@ -0,0 +1,15 @@
+package models
+
+// GrantTable is the name of the table the 'Grant' model is stored in.
+const GrantTable = "grant"
+
+// Grant represents an access grant to a specific user
+type Grant struct {
+	Pk uint `gorm:"column:pk;primaryKey"`
+
+	User string `gorm:"column:user;not null;uniqueIndex:user_slug"` // (distillery) username
+	Slug string `gorm:"column:slug;not null;uniqueIndex:user_slug"` // (distillery) instance slug
+
+	DrupalUsername  string `gorm:"column:drupal_user;not null"` // drupal username
+	DrupalAdminRole bool   `gorm:"column:admin;not null"`       // drupal admin rights
+}