add stats for negative cache count
Merge pull request #140 from pantheon-systems/negative-cache

add stats for negative cache count
tests for performance analysis
Merge branch 'master' of github.com:pantheon-systems/fusedav
pthread_exit was mistake; trying to make sure log statements get output at shutdown
res back to original ret
Merge pull request #141 from pantheon-systems/valhalla-stats

Reverting from incorrect usage of pthread_exit
Merge pull request #142 from pantheon-systems/master

add stats for negative cache count