Fix "gitcc rebase" for new files in a folder

New files in a dir were filtered (rebase.py:249) and were not added because
they didn't exist yet in a CC view until performing Update in ClearCase
Explorer.

Perform "cleartool update" for each "checkindirectory version" folder
to get all its files in the CC view to allow retrieve lshistory on new files
properly.
Merge pull request #49 from phts/fix-rebase-new-files

Fix "gitcc rebase" for new files in a folder