[#224] Unify logging in CSV formatted files

Use tablib to easily create CSV formatted logs.

Changes to how the scripts log actions to use the new log format.
[#224] Add tablib to pip requirements
[#224] Fix bug where Cordaid is field partner

When Cordaid is a field partner to a project two partnership objects get
the same internal ID and IATI activity ID. Fix by only allowing support
partners to have internal ID.
[#224] Fix non-integer indicator values

Some indicator values from Cordaid are percentage floats, e.g. 6.4. The
Benchmark.value field is an integer field so these values have to be
rounded.

Fix by adding IATIBenchmarkResource.hydrate_value. Note that this method
sets value to 0 on all errors, if an exception occurs this should be
logged for traceability.
[#268] Add Piwik analytics

Add django-piwik to requirements

Add settings for Piwik

Add template tags in rsr/base.html and partner_sites/base.html for Piwik
[#268] Add Piwik template tags to widgets
Updating .gitmodules to use https instead of ssh - fix issue with vagrant complaining about repo access
Merge pull request #269 from akvo/develop

Develop