Merge pull request #1 from dbetebenner/master

Update of SGPdata to 2012 with modifications to accomodate data.table 1.8.2
Merge pull request #2 from dbetebenner/master

Update of sgpData_LON
Merge pull request #3 from dbetebenner/master

Update of README.md
Merge pull request #4 from dbetebenner/master

Update to 4.0. Changed GRADE to class character