[FIX] base: remove early size limit on author field

The default size limits set in base.sql are eventually superseded by the
actual limits (or absence of) when the DB schema is synchronized with
the Python model definitions.

However the list of modules (name, authors, descriptions, dependencies)
is loaded before this can happen. The length of the author field is one
case that can easily crash the database bootstrap process at that point,
should a module with a long author name be present in the addons path.

After schema sync, that size limit is lifted entirely (although Odoo Apps
does limit the max author name length to 512 at the moment, to prevent
abuse).

Fixes #5850

openerp/addons/base/base.sql

@@ -85,7 +85,7 @@ CREATE TABLE ir_module_module (
     website character varying(256),
     summary character varying(256),
     name character varying(128) NOT NULL,
-    author character varying(128),
+    author character varying,
     icon varchar,
     state character varying(16),
     latest_version character varying(64),