[#710] Use ugettext instead of ugettext_lazy

ugettext_lazt causes problems when used in Country.fields_from_iso_code()
and since iso3166.py is "static" I can't see any problem with switching
to ugettext.
[#710] Enable filtering on ID for organisation

This simplifies the use of the API when looking for an organisation in
multiple ways.
[#710] Content ownership check and better error messages

Add check that no other organisation is the content owner when updating
organisations, and set the content owner to RAIN for created
organisations.

Better logging with more detailed errors.
[#710] Fix missing logo problem

Only add the logo key to the organisation dict if there is a logo to
fetch, otherwise the API protests.
[#710] Get correct data for internal_org_id field from RAIN XML
[#710] Change partnership API resource helper function get_organisation()

It now tries to find an organisation first by IATI ID and then by internal
organisation ID.
[#710] Better errors for rain_project_upload.py