Fix Mongoid documentation link

URL was moved over time, new official link is this one according to https://rubygems.org/gems/mongoid
Replace named controller name in path with mapping path. Fixes #772
It was okay.
Merge pull request #1001 from ujifgc/fix772

Replace named controller name in path with mapping path. Fixes #772
Merge pull request #998 from ujifgc/master

Improvement of Padrino's load speed
Merge pull request #999 from hooktstudios/mongoid-doc-link

Fix Mongoid documentation link
Lazily load the mail gem without autoload

This implementation uses the lazy sinatra settings system instead.

At worst, it can lead to _padrino_mailer being set twice.
Merge pull request #1002 from skade/lazy-mail-without-autoload

Lazily load the mail gem without autoload