phpfpm_average: to eliminante division by zero

To fix issues by dividing with zero.
Fix graph label for phpfpm_connections

accepted.label != Idle
Rename README file
Re-format README file into markdown language
Add custom variable env.phppool to README doucmentation
Bugfix for code format in README
Merge pull request #19 from bionix/master

phpfpm_average: to eliminante division by zero