make local bucket disk usage follow symlinks
make local bucket disk usage follow symlinks

Change-Id: I778cac48bf45946534c20e260dff72d7563449ac
Reviewed-on: http://review.membase.org/5752
Tested-by: Aliaksey Kandratsenka <340b8e09ca65cd3fc686427fcfed17e87eaf61e2@gmail.com>
Reviewed-by: Aliaksey Kandratsenka <340b8e09ca65cd3fc686427fcfed17e87eaf61e2@gmail.com>

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