Fix CoordinatorClusterClocks' safeTimeInterval
Fix CoordinatorClusterClocks' safeTimeInterval

The safeTimeInterval was incorrectly set (due to a typo) smaller than
the update interval causing the safeTime to elapse before the safeTime
is updated.  The safeTimeInterval is now set to 3 seconds with the
update interval remaining at 1.5 seconds.

anirajk/RAMCloud,anirajk/RAMCloud,matrix207/RAMCloud,anirajk/RAMCloud,anirajk/RAMCloud,matrix207/RAMCloud,rstutsman/RAMCloud,utah-scs/RAMCloud,rstutsman/RAMCloud,alexandermerritt/ramcloud,matrix207/RAMCloud,utah-scs/RAMCloud,jblomer/ramcloud,SMatsushi/RAMCloud,SMatsushi/RAMCloud,rstutsman/RAMCloud,utah-scs/RAMCloud,matrix207/RAMCloud,alexandermerritt/ramcloud,jblomer/ramcloud,alexandermerritt/ramcloud,SMatsushi/RAMCloud,rstutsman/RAMCloud,jblomer/ramcloud,utah-scs/RAMCloud,utah-scs/RAMCloud,SMatsushi/RAMCloud,utah-scs/RAMCloud,rstutsman/RAMCloud,anirajk/RAMCloud,SMatsushi/RAMCloud,SMatsushi/RAMCloud,jblomer/ramcloud,matrix207/RAMCloud,anirajk/RAMCloud,alexandermerritt/ramcloud,jblomer/ramcloud,jblomer/ramcloud,alexandermerritt/ramcloud,rstutsman/RAMCloud,alexandermerritt/ramcloud,matrix207/RAMCloud