New feature zoom in/out added to Visualization (Viz.js)

Line charts have by default the zoom in/out feature enabled, the info
passed to the drawrings functions haven't changed. What changed
was how we handle the arrays and the info displayed by the
X axis. Also the Y axis is resized everytime the zoom in
Add backward compatibility with line charts with stacked = true

displayDSLines function calls to former code or new call with the
zoom feature depending on the stacked flag
Merge branch 'charts-zoom-in-out'
Comment useless data sources in basic_metrics dictionaries

Some metrics that are not being generated were breaking the tests.
They've been commented
Add missing metrics to JSON used for Jasmine tests
Fix errors in specification of Jasmine tests

Some tests were run against metrics that haven't been implemented
in GrimoireLib yet. This does not make sense, so they were removed
to avoid breaking the tests.