update travis config

use UNIT_TEST=1 so as not to have to worry about installed modules breaking the
tests of other modules
[WIP] test an experimental maintainer-quality-tools branch
Add the create FA PO button in LR line
Fix TypeError
Fix typo
add button to create a call for bids from a source
add button in the source to create an agreement PO
Fix flake 8
fix error on module installation

the xml files need to be ordered so that the xmlids are defined before they are
used.
always show unit_cost and total_cost in the source
fix problem at module installation

ensure xmlids are defined before they are used
experimental branch merged
allow budget overruns on sources

A strict check like that one is too rigid: it turns out that it can be
useful to send cost estimates that are over the limit.
Regroup currency and country in view
Remove button 'View Prices' as not usable
Reorder fields in LRL tree view
ui fix: align budget fields of LR line form
fix: take accounting outside inner groups
Add amount_total in tree view
fix typo in Purchase Requisition view