New features, performance improvement and bug fixes

• Add tooltip.position option - #833
• Add polyfill for phantomjs compatibility - #578 #838
• Add data.selection.draggable and fix scrolling issue - #215 #798
• Add onrendered callback - #880
• Add axis.y.inverted and axis.y2.inverted - #885 #534
• Remove data.ondragstart and data.ondragend callbacks - #215 #798
• Improve performance by avoiding updating arc targets when it's not needed - #172
• Improve performance by skip transition when transition.duration = 0 - #172
• Fix to free detached DOM tree when destory called - #866
• Fix padding.left when rotated category axis - #872
• Fix generateColor for arc chart - #874
• Fix d3 dependency to <=3.5.0 - #893
• Fix tooltip width to have auto - #832
• Fix data.labels.format - #854
• Fix tooltip position when arc and legend right - #847
• Fix axis.y.min/max when it's inverted - #885
• Fix x grid height with padding.top - #903
• Remove useless files in bower - #869