Add a gitignore file.
Add node package.json
Add Gruntfile
Add tests architecture
Init web architecture
Add first version of the sources
Change test procedure to allow white box tests
Test crossfilterServer.size function
Test crossfilterserver.dimension function
Test crossfilterServer.dimension.filter function

This test that the filter function behaves as the others filter
functions depending on the parameter type but does not test that these
functions have the expected behaviour.
Test crossfilterServer.dimension.filterExact function. WIP

This does not verifiy the effects of emptyDatasets, so it should be
completed. But the emptyDatasets call in filterExact should probably be
removed since it it already called in the calls.
If we take the specs as backbox tests, we should test the effects of
emptyDatasets with filterExact, but can avoid it if specs are whitebox
ones.