update jgit to use same version as jenkins plugin (2.2.0)

Change-Id: I84fe850fdc2746458cfdfc761841f0960265da6b
Reviewed-on: https://q.tasktop.com/alm/s/c2c-oss/gerrit/133
Tested-by: Hudson
Reviewed-by: Michael Nelson <michael.nelson@tasktop.com>
Reviewed-by: Myles Feichtinger <myles.feichtinger@tasktop.com>
Tested-by: Myles Feichtinger <myles.feichtinger@tasktop.com>