Update scale_y_continuous.py

Parameter 'labels' can be used to manually designate labels in R.
Merge pull request #264 from Xbar/patch-1

Update scale_y_continuous.py
fix typo in word Exception
fix imports in geom files
Merge pull request #268 from cosinequanon/fix-geom-imports

fix imports in geom files
Merge pull request #267 from cosinequanon/fix-typo-in-geoms

fix typo in word Exception
Change legend and handle fill and alpha mapping

- legends are no longer added to ggplot object
- fill aesthetic mapping implemented
- alpha aesthetic mapping implemented
- moved legend code from ggplot.py to legend.py
- ':::*_mapping:::' hack to avoid collisions
Merge pull request #271 from has2k1/refactor-legend-fill

Change legend and handle fill and alpha mapping
fix imports and namespaces in qplot

- Move tests from wrong directory
- Faulty identification of geom_bar "fixed" by removing the
  guess and in the test, after all geom_bar is the same as
  geom_histogram and the current difference will be fixed in
  an upcoming commit (PR #266)
Merge pull request #277 from has2k1/fix-qplot-imports

fix imports and namespaces in qplot
bump version
importing ggtitle
bump
Merge commit 'a3143112a082f97e2dec5d7e880e59cce84a4b7c'