Do not force DROP FUNCTION but rely on CREATE OR REPLACE

We'll bet on no old signature being left around.

Presence of an old signature would break at runtime
with a message like:
ERROR:  function CDB_UserTables() is not unique

Closes #25
Do not enable DDL triggers on extension create

Use cartodb.cdb_enable_ddl_hooks() to enable them.
Closes #19
Tag CDB_TableMetadata as a configuration table

Closes #21
Try to cast TEXT typed updated_at and created_at if present

If the cast fails we'll still rename those fields and create
new ones. See #27 (cartodb_id is still not done)
Try to retain existing cartodb_id values

Also reset sequence when original cartodb_id values correctly
cast to integers, and does not keep a backup in that case.

Closes #27
Make time interval test not dependent on intervalstyle

Fixes testing from under cartodb/lib/sql
Set version to 0.1.0
Improve error message on failing CDB_CartodbfyTable
Back to 0.1.0dev version (aborted final)
Encode dependency of cartodb.control on Makefile
Fix cartodbfication of already-cartodbfied tables in presence of views

Closes #30
Includes testcase
Encode dependency of cartodb_version.sql on Makefile
Set version to 0.1.0 again
Move DDL triggers and extension postamble under scripts-available

Target 0.2.0
Add tool to create upgrades
Do not install cartodb_version.sql in system dirs
Fix recursive DDL trigger on create table

Closes #32
Provide upgrade paths

Mainly from 0.1.0 and 0.1.1
Includes 0.2.0dev to next and back
Ensure cartodb_id uses an associated sequence

Closes #33
Update NEWS file (0.1.1 will likely not happen)