Change type of cells.deleted from boolean to integer.

Fixes bug #1168490

Migration 152 changed other tables' deleted column from boolean
to integer, but cells got missed.  SQLite and MySQL are weakly-
typed enough that mixing integers and booleans is allowed, but
PostgreSQL is not, and this causes an error.

Migration 179 is a copy of migration 152, except applied only to
the cells table.

Change-Id: I85c39765edc206d38d21827ab54e1371155b9557
Merge "Change type of cells.deleted from boolean to integer."