Fix #10 #23 #24 #25 #34

Fixed #10 (closed), #23 (closed), #24 (closed), #25 (closed), #34 (closed):

• #10 (closed) Added linked account in Genesis.
• #23 (closed) Decoupled Identity and Smith by using a foreign key for Smith.
• #23 (closed) Added the number of forged blocks, the last forged block, and the last block at which the Smith status changed.
• #25 (closed) Added common chain stats.
• #34 (closed) Fix crash when multiple identities are created for the same account.

assets/sql/EnumsMigration_down.sql

 DROP TABLE IF EXISTS item_type;
 DROP TABLE IF EXISTS counter_level;
-DROP TABLE IF EXISTS identity_status;
 DROP TABLE IF EXISTS smith_status;
+DROP TABLE IF EXISTS identity_status;
 DROP TABLE IF EXISTS event_type;
+DROP TABLE IF EXISTS smith_event_type;
 DROP TABLE IF EXISTS comment_type;