Merge tag '0.1.5' into develop

add more options. update to c3#0.3
add subchart toggle
add custom legend
replace demo pages with a single page app
add additional demo files
more demo files for json
add examples for rows and axis
make type selector optional
reoranize tests
hide subchart if not enabled
update to angular 1.3.x
move schema out of data in an own object
rename identifieres from name to key and add name as custom lable
update README for schema and identifier naming
Merge branch 'feature/attributes' into develop

Introducing schema as an own object outside of the dataset.
To avoid confusion and to allow specific naming of columns all identifiers
are now call 'key'. The 'name' attibute can therefor be used for optional
descriptive naming.
jslint the code
add demo for selections
redraw chart when data changes
add pre- and postfix when defined in schema
add options for zoom and callbacks for events