Update netstats.py

Put tcp_attempt_fails percentage in correct metric group
Updated to handle Buffer pool size, bytes 5575016448 and individual buffer pool info not overwriting the totals.  This may only exist in percona, but the changes are backwards compat with what was existing
Merge pull request #111 from deeno35/master

Update to handle Percona's show engine innodb status
Update multi_interface.py to not bail out on metric_cleanup function

Error:

$ sudo gmond -m
Unable to find the metric information for 'procs_blocked'. Possible that the module has not been loaded.

Unable to find the metric information for 'procs_created'. Possible that the module has not been loaded.

Unable to find any metric information for 'softirq_(.+)'. Possible that a module has not been loaded.

AttributeError: 'module' object has no attribute 'metric_cleanup'

Further checking, it revealed that multi_interface.py does not metric_cleanup function defined.
Merge pull request #112 from mnikhil-git/patch-1

Update multi_interface.py to not bail out on metric_cleanup function