Remove delete post button from meetings

Prevent stacking offers

Fix delete post. Add mail for offer accept/decline

Add license

Add delete button to posts

Fix duplicate appearances in search

Remove mongo gems. Add post and author censoring

Fix ISBN validation on /selling

Fix gitignore. Further /offer fix

Fix duplication of /offers and /sales

Fix display of active offers on /offers

Fix /selling blank input

Refactor. Add basis for tests.

Update gitignore

Delete db from repo