Add MongoDB ActiveRecord library for CodeIgniter

Source: https://github.com/alexbilbie/codeigniter-mongodb-library/tree/v2
License: MIT License

Config file currently set up to connect to MongoDB database with no password. Once live server is set up, config file will (obviously) need to be edited to match the password of the MongoDB installation there.
Add MongoDB session library for CodeIgniter

Source: https://github.com/sepehr/ci-mongodb-session
License: CodeIgniter License Agreement
Improve session cookies

Based on the advice at http://christopherickes.com/web-app-development/3-codeigniter-sessions-best-practices/, I've turned on encrypted session cookies, and removed the underscore from the session cookie name (which allegedly causes problems in IE -- the only facts I could find to back up that claim had to do with underscores in domain names, not in cookie names, but in this case it won't hurt to be extra cautious.)
Add Ion Auth 2

Note: After pulling this commit, you need to go to the src/ directory and run "mongorestore sql/mongo". The sql/ directory can then be deleted, as this is a one-time setup to load Ion Auth's user & group collections into MongoDB.

Source: https://github.com/benedmunds/CodeIgniter-Ion-Auth (branch 2)
License: Apache License v2.0
Config changes to enable MongoDB with Ion Auth

Default Mongo database name is "mongo" for now, but we
could easily change that to whatever we want: sfweb, maybe.
Autoload the Ion Auth library
Use a (randomly-generated) session encryption key
Use bcrypt instead of SHA1 - much more secure

Note that the Mongo database will need to be updated to
set the admin password to the bcrypt hash for "password";
the syntax for doing this (assuming you've already loaded
the starter data that Ion Auth provides) is as follows:

db.users.update({'email': 'admin@admin.com'}, {'$set': {'password': '$2a$07$SeBknntpZror9uyftVopmu61qg0ms8Qv1yV6FG.kQOSM.9QhmTo36'}})
Make Login button on front page functional

Note that the "Create an account" (registration) link is not yet
functional, so the Login button isn't as useful as it could be.
Fix a few Ion Auth-Mongo bugs

Most of these bugs are caused by mild mismatches between
how Mongo returns rows and how an SQL database returns
rows: the SQL database apparently returns them as a hash
table (a dict in Python terms), whereas the Mongo connector
appears to be returning rows as arrays (lists in Python terms).

I'll eventually want to submit this to the Ion Auth issue
tracker on GitHub.
Merge branch 'master' into feature/auth

Conflicts:
	src/views/templates/header.html.php
changed config to remove index.php
made ion auth templates work with our SF templates
mongodb suppress connect error = false
renamed mongo sql to scriptureforge sql folder
removed welcome controller and view
added gravatar support in header; got auth pages integrated
added gravatar support
New script to setup default auth data

I've chosen to put this in scripts/ rather than in src/ because
I really don't think we want to allow running it from the web,
even by accident.
Merge branch 'feature/auth'