Created support for labels

Created support for the labels object in the fake starteam so that the
label can be used in the git-starteam syncronizer.

Also added the creation of labels to the fakestarteam builder so that
making them is easy enough.
Embed label support inside the GitImporter.

We make sure the label are sorted by date before using them. Optimisation
on the client side of the SDK could prevent a proper ordering of the
labels.

Also added most needed utility for labels processing.
Converted InvalidOperationException as NullPointerException.
Merge remote-tracking branch 'origin/master' into label-support

Get the lastest fix done on the master branch so we do not diverge too much.
Merge remote-tracking branch 'origin/master' into label-support

Fix have been done for the view configuration state. Modification done
need to some more tuning to work properly with label based import.
Added some logic to find the label time when the janitor is needed.
prevent gooing trought all labels when we have no new.
Use the default platform java.
Set the to string to put CommitInformation more verbose
Make a refresh of all files id.

This way we can find the deleted files more easly.
Save the files informations only when doing checkpoints and disposing

Otherwise when we did a resume, the files information would not be the
same as what was recorded during the sucessful importation.
Put a significant name, g means nothing. importer is better.
Improve message for readability
Find the enumeration representing the given octal string
Enable comparaison of SHA1Ref object with an other DataRef
Support for the Null Type as a possible Git File.

The octal number is used inside logs and is useful for identification of
file addition or deletion. We use it during the parse operation of the log
entry for validation and future export.
We don't need to find the last modified time for this strategy.
Add more comments for the RepositoryHelper
Improve the file registration for new files.
Make a refresh pass of all file at the start of the import process.

This way if we discover some new files, at least we can more easily track
them.