initial mysql support

migrations/mysql/2018-05-25-232323_update_attachments_reference/up.sql

@@ -0,0 +1,14 @@
+ALTER TABLE attachments RENAME TO oldAttachments;
+
+CREATE TABLE attachments (
+  id          VARCHAR(40) NOT NULL PRIMARY KEY,
+  cipher_uuid VARCHAR(40) NOT NULL REFERENCES ciphers (uuid),
+  file_name   TEXT    NOT NULL,
+  file_size   INTEGER NOT NULL
+
+);
+
+INSERT INTO attachments (id, cipher_uuid, file_name, file_size) 
+SELECT id, cipher_uuid, file_name, file_size FROM oldAttachments;
+
+DROP TABLE oldAttachments;