[collectd] fscache plugin

[Edward Konetzko]

Octo

I have been looking over the changes you made to the patch and they seem 
to be working fine.  I do have one question though about the metrics.  
Host and Plugin I understand perfectly, Plugin instance, type and type 
instance I am a little fuzzy on.  Currently all metrics are broken down 
at the plugin instance level, where it seems to be that should be the 
single type fscache_stats and type should be Aquires, Allocs... and then 
the type instance should be the metrics related to type.  To me it seems 
that model would allow for adding additional types of metrics later if 
the kernel module exposes more.  

I will work on another patch for if you want to go this direction, 
should have it done by tonight.

Edward