[IMP] base_external_dbsource: Refactor & Split by source

* Heavily refactor code for reusability
* Split all sources into independent modules
* Add more test coverage
* Add CRUD methods
* Add iterator execute return to roadmap

[UPD] Update base_external_dbsource_mssql.pot

base_external_dbsource_mssql/models/__init__.py

@@ -0,0 +1,3 @@
+# -*- coding: utf-8 -*-
+
+from . import base_external_dbsource

base_external_dbsource_mssql/models/base_external_dbsource.py

@@ -0,0 +1,45 @@
+# -*- coding: utf-8 -*-
+# Copyright 2011 Daniel Reis
+# Copyright 2016 LasLabs Inc.
+# License LGPL-3.0 or later (http://www.gnu.org/licenses/lgpl.html).
+
+import logging
+
+from odoo import api, models
+
+_logger = logging.getLogger(__name__)
+
+try:
+    from odoo.addons.base_external_dbsource.models import (
+        base_external_dbsource,
+    )
+    CONNECTORS = base_external_dbsource.BaseExternalDbsource.CONNECTORS
+    try:
+        import pymssql
+        CONNECTORS.append(('mssql', 'Microsoft SQL Server'))
+        assert pymssql
+    except (ImportError, AssertionError):
+        _logger.info('MS SQL Server not available. Please install "pymssql" '
+                     'python package.')
+except ImportError:
+    _logger.info('base_external_dbsource Odoo module not found.')
+
+
+class BaseExternalDbsource(models.Model):
+    """ It provides logic for connection to a MSSQL data source. """
+
+    _inherit = "base.external.dbsource"
+
+    PWD_STRING_MSSQL = 'Password=%s;'
+
+    @api.multi
+    def connection_close_mssql(self, connection):
+        return connection.close()
+
+    @api.multi
+    def connection_open_mssql(self):
+        return self._connection_open_sqlalchemy()
+
+    @api.multi
+    def execute_mssql(self, sqlquery, sqlparams, metadata):
+        return self._execute_sqlalchemy(sqlquery, sqlparams, metadata)