Adding RRD handler.

This allows us to store Diamond data in RRD files.
RRD is a general purpose format for storing time-based
data and allows for aggregation to efficiently track
data at different resolutions.

Signed-off-by: Adin Scannell <adin@scannell.ca>
Merge pull request #429 from amscanne/add_rrdtool_handler

Add handler for generating RRD files.
Additional logging for MySQL collector
Merge pull request #430 from faridsaad/mysql_logging

Additional logging for MySQL collector
Doc updates
PEP8 fixes
Fix tox deps
Fix travis-ci requirements
py25 fixes
Ignore None stats from postgres
Merge pull request #431 from dctrwatson/psql-ign-none

Ignore None stats from postgres
Fixed nameclash with mysql-connector-python. The fix makes
module directory (collectors_path) higher priority over
site-packages.
GridEngineCollector for Univa Grid Engine/Open Grid Scheduler
Merge pull request #435 from elconas/master

Fixed nameclash with mysql-connector-python. The fix makes
Merge pull request #436 from jgoldschrafe/gridengine

GridEngineCollector for Univa Grid Engine/Open Grid Scheduler
Fix an issue with the string formatter and being split over newlines
Try to fix an issue where the apcupsd collector can crash the server process.
PEP8
python 2.5 compat
python 2.5 compat