Add RawFileStore.getFileId for in-place import

In order to be able to find the right location to symlink
the file, it's necessary to find the originalfile object
for upload *before* verifyUpload() has been called.
Fix minor issue in import_candidates.py
Whitespace fixes
Update header
Add simple integration test
Merge pull request #2007 from snoopycrimecop/rebased/develop/get-file-id

RawFileStore.getFileId (rebased onto develop)