Add background task to generate the general highlights on the mainpage

Gemfile

Gemfile.lock

app/controllers/welcome_controller.rb

app/repositories/active_record/dspace_repository.rb

app/repositories/orient_db/dspace_repository.rb

app/repositories/orient_db/main_page_repository.rb

app/views/welcome/index.html.erb

config/initializers/repositories.rb

config/initializers/task_scheduler.rb

config/orientdb.yml

lib/tasks/mainPage.rake