add EmergencyRoom.add

git-svn-id: https://markus.cdf.toronto.edu/svn/csc207-2014-09/group_0909@84 8153ec5e-17d7-4962-8641-23ff7c14a8d4
start reading patients from database

git-svn-id: https://markus.cdf.toronto.edu/svn/csc207-2014-09/group_0909@85 8153ec5e-17d7-4962-8641-23ff7c14a8d4
implement reading visits

git-svn-id: https://markus.cdf.toronto.edu/svn/csc207-2014-09/group_0909@86 8153ec5e-17d7-4962-8641-23ff7c14a8d4
use isNull method instead of checking against null

git-svn-id: https://markus.cdf.toronto.edu/svn/csc207-2014-09/group_0909@87 8153ec5e-17d7-4962-8641-23ff7c14a8d4
use visit IDs

git-svn-id: https://markus.cdf.toronto.edu/svn/csc207-2014-09/group_0909@88 8153ec5e-17d7-4962-8641-23ff7c14a8d4