DST fixes for 0.9.x

Backports from @brutasse's graphite-api.
Fixes issue #810.
Ah, forgot to add second @brutasse commit
Another oops
More fixes, trying to patch fetchData
Removing unneeded parts
Following @brutesse's advices :)
Right (tm) test provided
Oops, test was wrong
Ah, wrong format
Screw it, let's just check if it's the same for different timezones. Have no idea why result differs from results on master branch...
Hmmm... Trying set explicit timezone.
Proper fix (tm) for time values, test MUST working now
Merge pull request #989 from deniszh/0.9.x_dst_fixes

0.9.x dst fixes