Format UUID with leading zeros.
Format UUID with leading zeros.

The generated UUIDs will now always be formated as xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx.

Change-Id: I048b0ea122447655a02e4030046cea3937ac029f
Reviewed-on: http://review.membase.org/5681
Reviewed-by: Aliaksey Kandratsenka <340b8e09ca65cd3fc686427fcfed17e87eaf61e2@gmail.com>
Tested-by: Aliaksey Kandratsenka <340b8e09ca65cd3fc686427fcfed17e87eaf61e2@gmail.com>

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