Require cartodb extension 0.2.1

Fixes:

 - Do not create duplicated indices on cartodb_id
 - Do not force cartodbfication of existing functions
 - Ensure pg_catalog objects are found before public ones, fixing
   upgrade of databases with public tables named after standard
   data types (ie: "text", "date")
CDB-3212 Rake prepared
CDB-3212 Small rake improvement, literal typo
CDB-3212 improved logs, separated in files per-rake
Merge pull request #532 from CartoDB/CDB-3212

Cdb 3212