implement adding Visits to database

git-svn-id: https://markus.cdf.toronto.edu/svn/csc207-2014-09/group_0909@141 8153ec5e-17d7-4962-8641-23ff7c14a8d4
implement writing Patients to database

git-svn-id: https://markus.cdf.toronto.edu/svn/csc207-2014-09/group_0909@142 8153ec5e-17d7-4962-8641-23ff7c14a8d4
implement writing VitalSigns to database

git-svn-id: https://markus.cdf.toronto.edu/svn/csc207-2014-09/group_0909@143 8153ec5e-17d7-4962-8641-23ff7c14a8d4