add tick format
add stack chart and test title

# Please enter the commit message for your changes. Lines starting
# with '#' will be kept; you may remove them yourself if you want to.
# An empty message aborts the commit.
# On branch master
# Your branch and 'origin/master' have diverged,
# and have 6 and 1 different commit each, respectively.
#   (use "git pull" to merge the remote branch into yours)
#
# Changes to be committed:
#   (use "git reset HEAD^1 <file>..." to unstage)
#
#	modified:   bower.json
#	modified:   lib/veasy.js
#	modified:   package.json
#	modified:   src/veasy.coffee
#	modified:   test/area_test.coffee
#	modified:   test/bar_test.coffee
#	modified:   test/chart_test.coffee
#	modified:   test/flow_test.coffee
#	modified:   test/line_test.coffee
#	modified:   test/multiple_test.coffee
#	modified:   test/pie_test.coffee
#	modified:   test/scatterplot_test.coffee
#	modified:   test/stack_test.coffee
#	modified:   test/veasy.js
#