Match behavior of other backends for searching the metrics tree
quote series names so that influx knows the special chars are part of
the name.
Fill missing values (within the step interval) with None values

Provide functional compatibility to whisper db, where missing
values generate None (null).
Without filling the gaps, Graphite-Web is generating wrong graphics.
bugfix: when we need to fill in None, assure right amount of points
fix off-by-one error
assure from/end behavior is same as graphite
fix: specify steps more robustly

by just querying influx for datapoints, there's a chance
you're missing values (i.e. nulls in graphite) in influx,
so you can't rely on the next point for calculating the step.