swarming: Reload the google py library after initializing a bot's path.
swarming: Reload the google py library after initializing a bot's path.

This should allow bots that already have old python protobuf versions installed use ts_mon.

BUG=643378, 634559

Review-Url: https://codereview.chromium.org/2496803002

luci/luci-py,luci/luci-py,luci/luci-py,luci/luci-py