[#14] Refactor: add template helpers to main plugin
[#14] Add homepage plugin.

Inserts content from a JSON file into homepage.
Merge branch '11-template-tweaks' into next
[#15] Update list of strings for translation (ckan.pot file).
Merge origin/next
[#14] Update home.json demo content
[#14] Update homepage content block so py:with var only applies to relevant div
[#14] Add maintenance message to homepage
[#14] Change 'view all' link for most viewed datasets to search page sorted by views
Refactor: remove ECPortalHomeController and clean up home/index.html
[#11] Separate visualisation and non-visualisation resources
Merge origin/next