Graphite: only part of timerange in result #65

[rozetko]

Fixes #65

Problem

Result contains only part of queried dataset For example, you're trying to query data from 18:00 to 17:00 but only get 18:00 - 9:00

Reasons

• moment converts data to OS timezone instead of UTC
• we used 12-hour hour format (h) instead of 24-hour (hh)

Changes

• use timestamps in seconds instead of formatted data
• fix test