Support :rfc1034identifier in Info.plist processing.

Example projects have been updated to test it.

Task-number: QBS-465
Change-Id: I6e444512132293f7466e5f6372fdae12645c9db1
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
Update docs to mention $(VAR) form in Info.plist processing.

Change-Id: Icea0faa06ceee110406a21c4718eba1a54e03f80
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>