* fixed formating/comments in users schema

* channels schema now uses a bigint unsigned for pid
this is to keep consistent with notion of id's being usize|u64 in rust
* foreign key constraint added to keys table referencing user rows

server/migrations/2020-03-11-005217_channels/up.sql

@@ -1,5 +1,5 @@
 CREATE TABLE IF NOT EXISTS `channels` (
-    `id` INTEGER NOT NULL auto_increment,
+    `id` BIGINT UNSIGNED NOT NULL auto_increment,
     `name` VARCHAR(255) NOT NULL,
     `description` VARCHAR(1024),
     `kind` INTEGER NOT NULL,