common/perf_counters: Add 'perf reset all|perfcountername' for 'ceph
--admin-daemon'

Using this command, we can reset all perfcounters or reset on specified
perfcounter.

Signed-off-by: Jianpeng Ma <jianpeng.ma@intel.com>
test/perf_counters: Add test case for cmd 'perf reset'

Signed-off-by: Jianpeng Ma <jianpeng.ma@intel.com>
test/perf_counters: Replace perfcounters_dump to perf dump.

The func of command  perfcounters_dump and 'perf dump' are the same .
But from the print 'ceph --admin-daemon help', it only print 'perf
dump'. So replace.
In order to keep consistent, still keep perfcounters_dump in code for
old user.

Signed-off-by: Jianpeng Ma <jianpeng.ma@intel.com>
common/perf_counters: Remove the duplicated code.

Signed-off-by: Jianpeng Ma <jianpeng.ma@intel.com>
Merge pull request #3028 from majianpeng/fix4

Add perf reset command.

Reviewed-by: Loic Dachary <ldachary@redhat.com>