chronic conditions check

Eric, we should go through this as I want to make sure the assumptions
I've made are correct and this is merged into the main dataset in the
right place
Had to reformat the icd-9 codes in stata and import as a csv since sas
has a bug and won't import stata 13 files
Updated start file to be mb_final dataset
If no dx code present in 12m prior to hospice enrollment, set chronic
conditions indicators to 0 since they have ffs medicare for that time
period