Added Tutorial 22 and Assignment 12

Squashed commit of the following:

commit 5ecc0b5929bc253f5400e648e99f1fdd8fe6e4ad
Author: Adam Ginsburg <keflavich@gmail.com>
Date:   Mon Apr 15 09:44:32 2013 -0600

    added title to tutorial

commit b03c9649a76ae8920f51b9a7fe61c1798d2313d9
Author: Adam Ginsburg <keflavich@gmail.com>
Date:   Mon Apr 15 00:14:50 2013 -0600

    21->22 in the pdf

commit cb3fe080ea9e1edf9b819407138a709ba8f062c6
Author: Adam Ginsburg <keflavich@gmail.com>
Date:   Mon Apr 15 00:13:27 2013 -0600

    moved tut21->tut22

commit d639659b0326ee190e5cbffee773304fe5c4ba82
Merge: a7e2dc0 be62388
Author: Adam Ginsburg <keflavich@gmail.com>
Date:   Mon Apr 15 00:12:43 2013 -0600

    Merge branch 'master' into staging

commit a7e2dc06d7f9ef4b8c582106b826ab85eddcfd89
Author: Adam Ginsburg <keflavich@gmail.com>
Date:   Mon Apr 15 00:12:33 2013 -0600

    added tutorial pdf

commit a1421fb6f31acd5ff20b9be73e832493a85c381f
Author: Adam Ginsburg <keflavich@gmail.com>
Date:   Sun Apr 14 23:40:01 2013 -0600

    added Tutorial 21 source code

commit 2318197e4e48eabf6c2aed03896a54a959f2aa92
Author: Adam Ginsburg <keflavich@gmail.com>
Date:   Sun Apr 14 23:30:16 2013 -0600

    added assignment12 on oop & classes & a little data fitting
Merge branch 'master' of github.com:ASTR2600s13/ASTR2600_class_materials

Conflicts:
	tutorials/tutorial22_datafitting.pdf
Merge branch 'master' of github.com:ASTR2600s13/ASTR2600_class_materials

Conflicts:
	tutorials/tutorial22_datafitting.pdf