refs #4022 Fix iframe attributes in privacy settings

Original fix was only applied to `plugins/CoreAdminHome/templates/generalSettings.twig`.
Revert "Do not load plugins that have their own git repositories, when executing tests"

This reverts commit 0bd88be286c83dc4b5dc65b45a5424ae71f38dca.
Fix diff viewer generation github links for plugin tests.
Fix bug in last commit.
Fix diff generation in screenshot tests for plugins (paths were not different for plugin tests).
Remove backtrace printing define from proxy so they won't appear in screenshot tests.
Fix diffviewer path.
refs #4691 wondering if we can easily enable travis for angularjs tests
refs #4691 install npm before running tests
refs #4691 added missing version field
refs #4691 should make sure we have latest node version
refs #4691 updated doc
refs #4691 assume yes to all queries
Do not call exit from within CronArchive class.
Add main() method to CronArchive to call individual methods.
Refactor console application entrypoint so  is not read from directly.
refs #4691 added more test cases
Merge branch 'master' of github.com:piwik/piwik
Update README.md
refs #4691 make sure to install correct package