refactoring of graphite panel to be more datasource agnostic, start of experimental influxdb support

allow hour, day, week and year time rounding

Added highestAverage / lowestAverage

This fixes the Basic Auth not working issue (issue#16) further, by
removing the auth string from the URL before grafana attempts to use
it. Some js doesn't handle it properly and tries to include the auth
string in dns lookups(?), so the request never even hits the graphite
server when an auth string is present.

added small text to show when no datapoints are returned and when datapoints returned from graphite are outside timerange (can happen when timezone mismatch) #143

Added the 'stacked' and 'lowestCurrent' functions

added exclude function

added movingAverage function

A lot more work on annotations (#44, #8). Graphite events is working, editing, icon size, color and vertical line toggle/options working. To sleepy now...

major improvement to how modals are loaded, much more reuse in html dom elements, hopefully solves #109.