Force Vertica to create default projections.

Otherwise, the first call to `LOCK changes` hangs. So we add an `ENCODING
AUTO` expression to a single column expression in each table. This forces
Vertica to create the default projection at table creation time, as described
in the "Automatic Projection Creation" section of the CREATE TABLE
documentation:
http://my.vertica.com/docs/7.1.x/HTML/index.htm#Authoring/SQLReferenceManual/Statements/CREATETABLE.htm.