added an error message in project:freeze if the given symfony data dir does not exist (closes #3419)
added an error message in project:freeze if the given symfony data dir does not exist (closes #3419)

git-svn-id: 7038a89b398528086dab5106cc8d05243a854dbc@8809 ee427ae8-e902-0410-961c-c3ed070cd9f9

theodo/symfony1.1-backports,theodo/symfony1.1-backports,theodo/symfony1.1-backports