Update already imported products on calling update catalog #1981 fixes #69

Allow updation of products when the catalog update is called and the product
already exists in OpenERP.
Also allow updation of products from websites.
This allows user to choose which website info will be used a the principal
value.
Update travis for new repo name #2002
Forgive when order state is unknown #2013 fixes #79

The order status map only has a state for known values. For unknowns the
code should just leave the openerp state empty.
Export catalog to magento #2008 fixes #68

Export products from openerp to magento.

All the products selected for export will be exported to a category, attribute
set chosen by the user from a wizard. The exported products will always be
exported as simple products as other product types need attribute management
which better be left to magento. Other required details like weight, tax class
etc will be hardcoded to some default values which can later be configured on
magento itself.
Import category tree based on ID specified on website #2096 fixes #89

The category tree import might fail sometimes if no ID is provided. Explicitly
allow the user to define the magento ID of a category on website and use it to
import category tree.
Also fix a wrong string for a button in XML.
Add instance to context for shipment status export #2126 fixes #97

When export shipment status is called from cron it
does not have the magento instance set in context.
This patch sets the instance to context.
Handle context gracefully fixes #123

Context is defined as None in method definition.
The cron call does not provide a context either.
Hence add a key to context only when its present else create new context