Wrong import of module base

[Guewen Baconnier @ Camptocamp]

The 'base' module is imported with 'import base'.

It impacts OpenERP 6.1 and 7.0.

In some conditions, it can lead to errors like the following:

<snip>
line 25, in <module>
    from openerp.addons.base_geoengine import geo_model
  File "/<snip>/src/server/openerp/modules/module.py",
line 139, in load_module
    mod = imp.load_module('openerp.addons.' + module_part, f, path, descr)
  File "/<snip>/src/geoengine/base_geoengine/__init__.py",
line 28, in <module>
    from . import geo_ir
  File "/<snip>/src/geoengine/base_geoengine/geo_ir/__init__.py",
line 22, in <module>
    from . import ir_model
  File "/<snip>/src/geoengine/base_geoengine/geo_ir/ir_model.py",
line 23, in <module>
    if 'geoengine' not in base.ir.ir_actions.VIEW_TYPES:
AttributeError: 'module' object has no attribute 'ir'

Replacing the import in `base_geoengine/geo_ir/ir_model.py` by:

`from openerp.addons import base`

It works correctly.

Note that all the others "shortcut" imports could potentially lead to the same error and should be replaced by the complete namespace starting from the `openerp` package.