log tap stats every 30 seconds during rebalance
log tap stats every 30 seconds during rebalance

Change-Id: I8657fe5c0822fcfca0ca74914ed941c99eb9ebaf
Reviewed-on: http://review.couchbase.org/15247
Tested-by: Aliaksey Kandratsenka <340b8e09ca65cd3fc686427fcfed17e87eaf61e2@gmail.com>
Reviewed-by: Aliaksey Kandratsenka <340b8e09ca65cd3fc686427fcfed17e87eaf61e2@gmail.com>

daverigby/ns_server,daverigby/ns_server,daverigby/ns_server,pavel-blagodov/ns_server,ceejatec/ns_server,membase/ns_server,nimishzynga/ns_server,membase/ns_server,nimishzynga/ns_server,mschoch/ns_server,daverigby/ns_server,t3rm1n4l/ns_server,mschoch/ns_server,vzasade/ns_server,membase/ns_server,mschoch/ns_server,ceejatec/ns_server,membase/ns_server,mschoch/ns_server,mschoch/ns_server,pavel-blagodov/ns_server,t3rm1n4l/ns_server,nimishzynga/ns_server,daverigby/ns_server,pavel-blagodov/ns_server,t3rm1n4l/ns_server,ceejatec/ns_server,ceejatec/ns_server,pavel-blagodov/ns_server,t3rm1n4l/ns_server,membase/ns_server,mschoch/ns_server,nimishzynga/ns_server,ceejatec/ns_server,t3rm1n4l/ns_server,nimishzynga/ns_server,vzasade/ns_server,ceejatec/ns_server,vzasade/ns_server,vzasade/ns_server,membase/ns_server,nimishzynga/ns_server