Fixed one test that didn't use the configured root URL

There was a hardcoded 'http://localhost', if you use a different port that 80 then the test fails
Created unified system for running tests in travis for Piwik Core and any Piwik plugin. System includes a console command (generate:travis-yml) that generates a .travis.yml file for a plugin or core. The travis file will check in travis if it needs to be updated, and if so it will fail the build and tell the user. If a specific command line option is specified supplying a github user token, the .travis.yml file will be updated within travis automatically.

Notes:

  - comments and non-travis sections will be preserved
  - includes logic for plugins to test themselves against latest stable version instead of just on master
  - the system is primarily controlled by environment variables. developers can change/add variables in .travis.yml and the auto-updating will preserve the changes.
.travis.yml file is out of date, auto-updating .travis.yml file.
Merge pull request #5967 from piwik/translationupdates

[automatic translation update] Updated 131 strings in 8 languages (ru, fr, sv, cs, da, de, el, it)
Temporary change to test for recursion detection. [.travis.yml file is out of date]
Revert "Temporary change to test for recursion detection. [.travis.yml file is out of date]"

This reverts commit 25c3bf0f63c86c53afdd52edbe8ebe3b9e718ba3.
Try removing redundant travis_retry.
source travis-helper.sh again for angular js tests.
Merge pull request #5962 from piwik/travis_system

Created unified system for running tests in travis for Piwik Core and any Piwik plugin.
.travis.yml file is out of date, auto-updating .travis.yml file.
fixes #5961 radio fields were not selected when editing a goal
refs #5949 prevent warning if a quantifier is used. Escape them to make sure they are not applied in filter
Add check for tests to travis.yml generation so generation does not occur if plugin has no tests.
refs #5936 started to work on removing files from core and the plugins directories that are no longer present in the new build
refs #5936 added many tests for the new filesystem methods to make sure they only delete the files they are supposed to do
refs #5936 added some phpdoc blocks
refs #5936 moved some business logic from controller into model which also brings the advantage to make it better testable. Controller should be always simple/small... removeGoneFiles() is not really testable as it uses the static filesystem and I did not want to make the code ugly to mock it... Looking forward to dependency injection
refs #5936 forgot to commit the tests
Fix YAML indentation error in generate:travis-yml command.
Fix more YAML indentation issues and only throw exception for no tests in generate:travis-yml when generating for a plugin.