disabling flush-behind option by default in write-behind
Conflicts:
	xlators/performance/write-behind/src/write-behind.c
enable direct_io for write-only files
fixed typo in fuse-bridge.c
* xlators/cluster/unify:
  - enhanced self-heal code.
  - fixed a segfault bug caused due to fd->inode_list list.
fd_create/fd_destroy wrapper functions
modified posix, client-protocol, unify to use them, afr and stripe pending
* enhanced unify's self-heal. Now its done only if inconsistancy is seen.

* corrected op_errno==EEXIST in case of create. Need to send open, but now
  corrected it to do a lookup before sending open.