Fix search_items and some typos/whitespace

[feynmanliang]

POST ../rest/rpc/search_items was broken because the stored proc was using the todos relation without prefixing with api schema. This fixes that and adds a REST unit test to check it.

Also cleaned up some typos and whitespace.

[ruslantalpa]

@feynmanliang thank you for the PR,
the code looks good.
I'll look into how I can make it a patch and apply it to https://github.com/subzerocloud/postgrest-starter-kit since I use that project as a base/upstream and this kit is a superset of that so it would be a good thing to have your work in both repos (the commit author will preserved)

Thank you