Gbib auto updates

By default the Gbib checks every 5 seconds if a flag file on the hgDownload server is more recent than the date of the last update of the Gbib.

If the file on hgDownload is newer, it will update itself:

1. Update all existing /gbdb files
2. Update all mysql files + patch the hg19 searchspec and hide some tracks on hg19
3. Update all hgcentral files + patch the blat server table