Update py-graphite-web to 0.9.12.

Changes in 0.9.12:
- Usage of django.utils.timezone breaks Django 1.3 compatibility
- Missing import in graphite.util breaks cache-queries

Changes in 0.9.11:
- Properly return an HTTP 400 on missing query parameter in metrics/search
  endpoint (dieterbe)
- cumulative() is now superceded by consolidateBy() which supports
  min/max/avg/sum (nleskiw)
- Make graphlot target host configurable for easier embedding (dieterbe)
- Allow graphlot graphs to be embedded for use in dashboard apps (dieterbe)
- When wildcarding, prefer matching metric files to directories with the same
  name (tmm1)
- New header design and css cleanups (obfuscurity)
- New composer button to open the target in graphlot (magec)
- timeshift() can now shift beyond current time, allowing better
  current-over-week charts (mgb)
- Unit scaling added to cactiStyle (drawks)
- Support RRD files in index.json view (obfuscurity)
- Support for alternate target[] url syntax (luxflux)
- New countSeries() function which returns the cardinality of a wildcard
  (obfuscurity)
- Bootstrap data for movingAverage and movingMedian (seveas)
- movingAverage and movingMedian now optionally take time periods to specify
  window size (danielbeardsley)
- jsonp support in events/get_data (gingerlime)
- Ace editor for manually editing dashboard json (jordanlewis)
- New stddevSeries(), timeStack() functions (windbender)
- Remove ugly graph image background in dashboard (frejsoya)
- y-axis divisors for determining y-axis scale are now configurable (wfarr)
- Allow any characters in axis labels
- Target grammar now supports scientific notation for numbers
- New identity() function (dieterbe)
- Update default color scheme (obfuscurity)
- Dont blow up on permissions errors while walking directories (log instead)
- Encourage users to set SECRET_KEY uniquely with a warning
- broken nPercentile() and related functions
- Python 2.4 compatibility in browser endpoint (dcarley)
- Missing URL parameters in composer load
- Fix to multiplySeries to return the expected type (nleskiw)
- Don't blow up when empty series passed to cactiStyle (mattus)
- Trailing commas in js breaking ie (nleskiw, davecoutts)
- Remove extra and unnecessary rendering while loading saved graphs
  (hostedgraphite)
- Broken entry of timezone in composer menu (hcchu)
- constantLine() not drawing across the entire graph (mattsn0w)
- SVG rendering broken when using secondYAxis (obfuscurity)
- Expect url-encoded octothorpes in colorList (magec)
- Display relative times properly in dashboard (daveconcannon)
- cactiStyle() blows up with empty series (eranrund)
- Remove problemmatic and unnecessary url encoding
- Several pathExpressions missing which caused trouble in certain function
  combinations (dieterbe,colby,kovyrin)
- Use non-linux-specific datetime formatter %I instead of %l (richg)
- Use os.sep properly for path separation (justinc)
- Negative numbers not allowed in yAxis input box
- scale() misreports itself in legend when using small decimals
- colorList incorrectly cast to an int in some cases (rckclmbr)
- removeBelow* menu items adding the wrong functions to target list (harveyzh)
- nPercentile renders it's name incorrectly (TimZehta)
- CSV rendering does not respect tz parameter
- Missing max interval in xAxisConfigs causes long-term graphs with few
  points to render with a 12hr axis config
- Stacked graphs not filling completely in staircase mode
- Stacked graphs and many drawAsInfinite() lines do not draw cleanly
- Graphlot does not handle event timestamps properly (matthew keller)
- sin() time() and randomWalk() incorrectly using float times (jbrucenet)
- legend height is incorrect when secondYAxis used (obfuscurity)
- Expanded wildcards in legends are misordered (dieterbe)
- Regression in formatPathExpression (jeblair)
- index.json returns leading periods when WHISPER_DIR does not endin
  a trailing slash (bitprophet)
- Regression in areaMode=all causes only the last series to be filled
  (piotr1212)
- Default to settings.TIMEZONE if timezone unknown (gingerlime)
- Negative filled graphs render from bottom rather than 0 (piotr1212)
- Composer and Dashboard XSS fixes (jwheare, sejeff)
- Fix persistence of tz aware datetime in non-postgres databases
- Fix insecure deserialization of pickled objects (CVE-2013-5093)
- Lots of documentation improvement (jeblair,bclermont,lensen,cbliard,
  hvnsweeting)