added authentication via api key for some limited api methods (fix #64)

src/main/java/com/commafeed/backend/model/User.java

@@ -31,6 +31,9 @@ public class User extends AbstractModel {
 	@Column(length = 256, nullable = false)
 	private byte[] password;
 
+	@Column(length = 40, unique = true)
+	private String apiKey;
+
 	@Column(length = 8, nullable = false)
 	private byte[] salt;
 
@@ -99,4 +102,12 @@ public class User extends AbstractModel {
 		this.lastLogin = lastLogin;
 	}
 
+	public String getApiKey() {
+		return apiKey;
+	}
+
+	public void setApiKey(String apiKey) {
+		this.apiKey = apiKey;
+	}
+
 }