Added height:100%. to .mgwt-ScrollPanel css class.

[waynerasmuss]

I think this is consistent with previous versions of MGWT. After upgrading to 2.0 from 1.1 I had problems with all my scroll panels. Granted, it wasn't a 1 to 1 conversion. After some trouble shooting I discovered that it was because the scroll panel was expanding to accommodate it's contents. This change fixed this problem globally for me. I think it also matched the expected behavior.

I understand that this change might be undesirable in other situations. Just wanted to throw it out there.