Add command line option to enable sync write mode on backups.
Add command line option to enable sync write mode on backups.

mrdiegoa/ramcloud,Frank-Wu/RamCloud,mrdiegoa/ramcloud,matrix207/RAMCloud,mrdiegoa/ramcloud,alexandermerritt/ramcloud,taschik/ramcloud,utah-scs/RAMCloud,jblomer/ramcloud,jblomer/ramcloud,jblomer/ramcloud,SMatsushi/RAMCloud,DavidLi2010/ramcloud,QingkaiLu/RAMCloud,QingkaiLu/RAMCloud,Frank-Wu/RamCloud,Frank-Wu/RamCloud,Frank-Wu/RamCloud,jcarreira/ramcloud,y-higuchi/ramcloud,SMatsushi/RAMCloud,jcarreira/ramcloud,DavidLi2010/ramcloud,behnamm/cs244b_project,IMCG/RamCloud,IMCG/RamCloud,mrdiegoa/ramcloud,rstutsman/RAMCloud,behnamm/cs244b_project,QingkaiLu/RAMCloud,SMatsushi/RAMCloud,matrix207/RAMCloud,Frank-Wu/RamCloud,rstutsman/RAMCloud,anirajk/RAMCloud,QingkaiLu/RAMCloud,alexandermerritt/ramcloud,behnamm/cs244b_project,jblomer/ramcloud,alexandermerritt/ramcloud,SMatsushi/RAMCloud,matrix207/RAMCloud,jblomer/ramcloud,DavidLi2010/ramcloud,taschik/ramcloud,utah-scs/RAMCloud,taschik/ramcloud,jblomer/ramcloud,anirajk/RAMCloud,taschik/ramcloud,matrix207/RAMCloud,matrix207/RAMCloud,QingkaiLu/RAMCloud,jcarreira/ramcloud,y-higuchi/ramcloud,IMCG/RamCloud,SMatsushi/RAMCloud,Frank-Wu/RamCloud,anirajk/RAMCloud,jcarreira/ramcloud,utah-scs/RAMCloud,utah-scs/RAMCloud,jcarreira/ramcloud,IMCG/RamCloud,IMCG/RamCloud,SMatsushi/RAMCloud,rstutsman/RAMCloud,rstutsman/RAMCloud,utah-scs/RAMCloud,taschik/ramcloud,DavidLi2010/ramcloud,DavidLi2010/ramcloud,IMCG/RamCloud,anirajk/RAMCloud,mrdiegoa/ramcloud,QingkaiLu/RAMCloud,rstutsman/RAMCloud,behnamm/cs244b_project,DavidLi2010/ramcloud,alexandermerritt/ramcloud,anirajk/RAMCloud,behnamm/cs244b_project,alexandermerritt/ramcloud,jcarreira/ramcloud,rstutsman/RAMCloud,y-higuchi/ramcloud,y-higuchi/ramcloud,y-higuchi/ramcloud,utah-scs/RAMCloud,behnamm/cs244b_project,mrdiegoa/ramcloud,anirajk/RAMCloud,alexandermerritt/ramcloud,y-higuchi/ramcloud,matrix207/RAMCloud