Remove "GAP must be set on accounts" constraint from erp5_accounting.

Activating constraints is the job of configurator.
I left account_type constraint though, because without this Balance Transaction
creation may not work as expected.

product/ERP5/bootstrap/erp5_property_sheets/PropertySheetTemplateItem/portal_property_sheets/Account/gap_category_existence_constraint.xml

-<?xml version="1.0"?>
-<ZopeData>
-  <record id="1" aka="AAAAAAAAAAE=">
-    <pickle>
-      <global name="Category Existence Constraint" module="erp5.portal_type"/>
-    </pickle>
-    <pickle>
-      <dictionary>
-        <item>
-            <key> <string>constraint_base_category</string> </key>
-            <value>
-              <tuple>
-                <string>gap</string>
-              </tuple>
-            </value>
-        </item>
-        <item>
-            <key> <string>constraint_portal_type</string> </key>
-            <value> <string>python: ()</string> </value>
-        </item>
-        <item>
-            <key> <string>description</string> </key>
-            <value> <string>GAP must be set</string> </value>
-        </item>
-        <item>
-            <key> <string>id</string> </key>
-            <value> <string>gap_category_existence_constraint</string> </value>
-        </item>
-        <item>
-            <key> <string>message_category_not_set</string> </key>
-            <value> <string>GAP must be set</string> </value>
-        </item>
-        <item>
-            <key> <string>portal_type</string> </key>
-            <value> <string>Category Existence Constraint</string> </value>
-        </item>
-        <item>
-            <key> <string>test_tales_expression</string> </key>
-            <value> <string>python: object.getValidationState() not in ("invalidated", "deleted")</string> </value>
-        </item>
-        <item>
-            <key> <string>use_acquisition</string> </key>
-            <value> <int>0</int> </value>
-        </item>
-      </dictionary>
-    </pickle>
-  </record>
-</ZopeData>

product/ERP5/bootstrap/erp5_property_sheets/bt/revision

-78
\ No newline at end of file
+79