Merge pull request #757 from akvo/develop

[#756] Astana hotfix 2.4.2
[#710] Add filtering to ProjectSaver._publish()

_publish() now published projects that have both an image and a location other than 0, 0.

Add logging for this too.
Merge branch 'release/candidate' into develop
[#796] Re-added Invoice signal
[#769] Added empty line at end of file
[#796] Added extra empty line before function
Merge pull request #819 from akvo/feature/796_paypal_code

[#796] Re-added Invoice signal