graphite.py: Clean up and refactor
remove cross graphs
Small changes in methods.py

to make compatible with the changes in grpahite.py
Fix disk and no-data series, other minor fixes
Make get_stats also accept custom graphite targets
Revert "Attempt to gracefully handle time skews"

This reverts commit f7f539187a7774f9b4fd5e04e2a27dd7098f660e.

Conflicts:
	src/mist/alert/alert.py
Make mist.alert compatible w graphite.py changes
alert.py: handle None's in datapoints
Make mist.alert work with custom metrics