Update dependencies

[rossjones]

A lot of dependencies that were chosen in 2010/2011 are still in use and have not been updated.

For instance, those that include celery (ckanext-qa for example) are using a version from 2011 even though Celery has undergone many improvements. The pika in use by ckanext-harvest is also from the same time frame.

I don't think this is a huge task, beyond finding out which ones are out of date, and ensuring tests pass, it might be a good place for someone new to ckan to start?

[davidread]

These appear to be the celery 3 changes, thanks to @Zharktas:

• ckanext-archiver https://github.com/yhteentoimivuuspalvelut/ckanext-archiver/commit/70c18c26afc6958822f6f2f12a4054af22d906d8
• ckanext-qa https://github.com/yhteentoimivuuspalvelut/ckanext-qa/commit/f828661edd25671a3cef4c03373e944fc615d78c

[TkTech]

The slim wrapper around Solr is also more or less abandoned. solrpy should be swapped in favor of pysolr which is maintained and has community momentum.

[deinok]

@rossjones I'm working on it Adding this Badge will help track Dependences https://requires.io/github/ckan/ckan/requirements/?branch=master