Feature/confirmation modal

this is my attempt to add modal confirmation on delete post, user and group.

Basically this work by adding routes to render the bootstrap modal, this is (as fair as i know) the only way
to create such diffrents modals that differs on the id to delete (done server side, maybe there is a better front end solution using more javascript).

I also added a section (body_bottom) before the </body>, in order to add custom HTML/script (actually the skeleton modal and the bootstrap modal trick).

Im sorry about some shitty commits, this is my first time in contribooting.