Activate scrollspy only if is enabled.
Editor performance improvements.

Create a new scope for the editor form and destroy it when form is reloaded.
Remove form elements to avoid larged detached DOM trees in Chrome.
Field directive : remove events on directive DOM elements added in the link function.
Editor / Add configuration to insert text element in the form #611.
Ignore rebel.xml files.
Merge remote-tracking branch 'upstream/stable-develop' into stable-develop