Remove visitor generator & security info from pluginsToLoad override.
Refs #3089, show visitor profile on 'returning visitor' icon click in real time visits widget, fix bug regarding visitorId API parameter, show correct tooltip for 'returning visitor' icon.
Refs #4151, remove loadJavascriptTranslations twig function and automatically generate translation JS for all plugins. Translation JS is now treated as an asset and is included in merged JS.

Note:
  - Includes tweaks to capture.js: on webpage error stop capture program.
Refs #4151, refactor translation JavaScript generation code and add event so plugins can specify which strings should be available client-side.
Refs #4151, make sure translations JS is always regenerated when merged assets is disabled.
Try to avoid random failure in UI tests on travis.