DAO clubuml116

Cherry picked some old commits.
Updated ProjectDAO to support multiple projects -- Added methods:
getProject(String projectName), 
addProject(Project project),  
updateProject(Project project),
disableProject(String projectName),
enableProject(String projectName)
isExisted(String projectName)
getAllProjects()
getDiagramContexts(String Project) //(To be implemented)
getUsers(int projectId)

Created Unit Test for these methods in UnitTest/ProjectDAOTest.java