Fixed creation of backend file in ConfigFileBackend

Ignore-this: 5f9ca41cbd5e986cdd13d4444a3cd7b8

darcs-hash:20090323115549-1e3d8-4d786cdf9ac115644ec98e0b7ee270c2b8da5be0
Added configuration datatypes DataFile and DataDirectory

Ignore-this: eff08f43f1f0b0bea4283b46f48dab06

darcs-hash:20090323115714-1e3d8-22242d3ff09ff9ab74ff0dc8e1d3b5d293374664