KWSys development is moving away from the Gerrit Code Review system.
Disable portions of `SetupForDevelopment.sh` related to Gerrit.

Add a version number to the `SetupForDevelopment.sh` script and use
a pre-commit hook to check when it changes.

GitSetup upstream added an attribute to export `.gitattributes` so that
importing snapshots into the sources of other projects would bring along
the attributes.  However, we don't want to export them from KWSys.  Drop
`.gitattributes` entries not relevant to KWSys.

Configure GitSetup scripts for KWSys.  Run them from a single
SetupForDevelopment.sh script.

Change-Id: Ic4f02175fd65e2f4fe5688e43313766c2b23458f