[FIX] Fixed NPE in ProjectImp.java

And reorganized FileImp imports.

Change-Id: Iecfcaff120df5e12319eafba9f8f4273153b64c9
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1818
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>
Reviewed-by: Holger Schmeisky <google@schmeisky.com>