fixed: error when .dproj file is from older Delphi version than used one
fixed: error when .dproj file is from older Delphi version than used one

In simple case can compile Delphi 2007 project with Delphi 2010, but
.dproj file sturcture is different. So, error occured while getting
version info. But it's just an absence of version info that should not
cause an error.

ashumkin/rake-delphi,ashumkin/rake-delphi,ashumkin/rake-delphi