add gradle support
Removed dead code, fixed centerViewPort(...) issue.
Merge readme.
Bugfix in the piechart, improved highlighting, added feature for space between slices.
Update README.md
Merge pull request #20 from dodocat/develop

Added gradle support.
Code cleanup.
Improved saveToGallery(...) method.
Adjusted gradle file.
Added chart in ListView example.
Added example with multiple chart types inside a ListView.
Update README.md
Started refactoring/changing the data model. Drawing in chart currently not working.
Update README.md
Worked on model. Added support for stacked bars. Legends currently not working, drawing by gesture currently not working.
Update README.md
Worked on PieDataSet and PieChart.
Added support for BarChart to have bar-shadows that show the maximum value.
Fix in stacked-barchart bar-shadows. Added typeface support for x- and y-axis labels.
Implemented ScatterDataSet.