added view for pie chart
added json view for charts
Added JSON route and linked chart view to it
Switched JSON endpoint to the chart itself to avoid using a separate controller action
added webmock gem
fixed charts spec
added specs for charts API
Mergg branch 'charts' of github.com:chartist/chartist into charts
Refactored specs
Added a test for CSV processing
Added size validation for the uploaded CSV
Added validation for csv files
Merge branch 'charts'
Merged charts branch with master
Fixed merge issues