Add search functionality to query.py

[xuset]

The query.py should search through all the models and all string attributes and return a page of results

[xuset]

Basic search functionality includes exact keyword matches on string columns. Also only the first 10 results are returned from each query regardless of whether there were better matches further down into the query. What is left is:

• non-exact match using the like operator
• search for non-string columns
• Don't limit the query. The query should return all the results then it should be sorted and truncated
• The results should also include the type of the item (post, user, comment, etc) so the frontend can distinguish

[xuset]

@jeknoebel is there anything else that needs to be added for search functionality or is it complete?

[xuset]

Closed in previous commits