Merge tag 'v1.6.1' into develop

1.6.1
Removed useless import (Topic) from models + reorganized imports
Added usage of django's social meta variables in base.dj.html
Added get_topic_model + is_member_of methods in detective.utils
Added entity, entity_list & topic views to detective.views for social meta injection #338
Added usage of entity, entity_list & topic for related views in app.urls
Added missing parameters to get_topic_model in entity view #338
Implemented topic view #338
Restored travis CI
Remove useless option
Fixed indentation
Updated readme
Remove some pip option
Added IRC notification
Added explicit settings for og:description, og:title + added og:url in base.dj.html
Replace topic.get_models by topic.get_models_module in app.detective.utils.get_topic_models
Many views improvement + added setting of url meta for all views
Fixed usage of non-existing entity attribute in entity_list view #338
Debugging meta - removed usage of static django tag for og:image
Set topic description as meta_description for entity_list view #338