Next round of updates to pmdagluster functionality
Next round of updates to pmdagluster functionality

Introduce a better scheme for managing volume and brick caches,
using a ctypes Structure for each.  Discovered a way to detect
whether volume profiling is enabled, so we can now export that
state via the storable metric value.  Added in dist, stripe and
replica count volume stats.

The XML parsing code is added here (thanks to Shishir Gowda for
his help there), and stitched into the PMDA refresh fabric.

mbaldessari/pcp,wuliming/pcp,adfernandes/pcp,tjanez/pcp,prasincs/pcp,edwardt/pcp,mbaldessari/pcp,andyvand/cygpcpfans,prasincs/pcp,adfernandes/pcp,mbaldessari/pcp,prasincs/pcp,mbaldessari/pcp,wuliming/pcp,adfernandes/pcp,edwardt/pcp,aeg-aeg/pcpfans,prasincs/pcp,edwardt/pcp,edwardt/pcp,tjanez/pcp,aeg-aeg/pcpfans,andyvand/cygpcpfans,aeg-aeg/pcpfans,andyvand/cygpcpfans,prasincs/pcp,tjanez/pcp,edwardt/pcp,prasincs/pcp,adfernandes/pcp,aeg-aeg/pcpfans,wuliming/pcp,adfernandes/pcp,mbaldessari/pcp,adfernandes/pcp,wuliming/pcp,wuliming/pcp,andyvand/cygpcpfans,andyvand/cygpcpfans,edwardt/pcp,aeg-aeg/pcpfans,andyvand/cygpcpfans,adfernandes/pcp,prasincs/pcp,mbaldessari/pcp,aeg-aeg/pcpfans,andyvand/cygpcpfans,wuliming/pcp,wuliming/pcp,andyvand/cygpcpfans,tjanez/pcp,adfernandes/pcp,prasincs/pcp,edwardt/pcp,aeg-aeg/pcpfans,tjanez/pcp,wuliming/pcp,edwardt/pcp,tjanez/pcp,tjanez/pcp,tjanez/pcp,aeg-aeg/pcpfans