Adding support for univariate GARCH models and demo

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/uwgarp@107 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
Updating and adding documentation for GARCH

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/uwgarp@108 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
Adding file for crsp weekly returns and garch file to sandbox

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/uwgarp@109 edb9625f-4e0d-4859-8d74-9fd3b1da38cb