introduce elasticity on both x & y axises for coordinate grid chart
updated guide to include x/y axis padding & elasticity setting
add x axis padding support for date
fix stackable chart elastic padded x axis calculation issue
improve bar x calculation to be more accurate representing underlying data
increase monthly volume bar height
update example page with guide on how to scope charts using grouping
add example for grid line rendering
dc.js v0.7 release sync
[issue #15] rename key/value retriever to accessor for better consistency w/ d3
change default bar centering to false
[issue #24] introduce bar gap setting to ensure equal distance is rendered between bars
add barGap in examples
[issue #32] update css to show user friendly indicators for interaction
add group based chart rendering doc
rename barGap() to gap()
[#issue 25] move grid line to background

 - moved grid line to background layer
 - improved grid line drawing logic to be more efficient
Merge branch 'gh-pages' of github.com:NickQiZhu/dc.js into gh-pages
add bubble chart by rounds in vc example
Merge branch 'gh-pages-dev' of github.com:NickQiZhu/dc.js into gh-pages