LU-2524 test: Clean up sanity-quota

LU-2524 test: Clean up sanity-quota

Conduct miscellaneous cleanup to sanity-quota including:
Removing the `-p` (parents) option from many calls to mkdir
Replace `lfs setstripe` with $SETSTRIPE
Added check for and call to `error` with error messages for a variety
of common routines ,like mkdir, or for functions that return a value.
Replace `…` with $(...)
Removed linefeed escape after |, ||, & and && operators.
Modified parameters in test 4b so that the --inode-grace value exceeds
the valid range.
Removed unused variables
Removed $ from variables inside $(())

Signed-off-by: James Nunez <james.a.nunez@intel.com>
Change-Id: Iadedea0bd0a0f85235e0bb908ee0a6ed36503eb3
Reviewed-on: http://review.whamcloud.com/14680
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Jian Yu <jian.yu@intel.com>
Reviewed-by: Wei Liu <wei3.liu@intel.com>
Reviewed-by: Saurabh Tandan <saurabh.tandan@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>