New search logic using ElasticSearch

Make the search to operate using HTTP requests instead of AJAX.
Adds pagination to the Search.
Move all the search logic into the SearchQuery model.
Add the SearchQuery controller to receive search requests.
Create the search index mapping for each model using a custom as_indexed_json method.
Use Foreman to start the PostgreSQL and ElasticSearch servers inside the vendor folder.
Make git ignore the vendor/postgresql and vendor/elasticsearch folders.