refs #6617 if process or output size is too large, declare it as finished

Declares a process as finished as soon as a PID file is > 500bytes
(contains only PID) and output file is > 100MB (which should usually
not be larger than 100KB or 1MB) to prevent files growing up to many
GBs. I added unit and integration tests for the file size detection. It is
now possible to mock the methods file_exists and filesize although very
simple so far. Later we can allow to define callbacks or to define different
return values for different files or we can use something like vfsStream
refs #6617 make sure to reset file mock after each run
to prevent calling parent::setUp/tearDown()
refs #6661 initial work on triggering a 400 bad request instead of 500 in case Idsite is wrong
refs #6661 in case value is empty set a default
refs #6661 undoing this change to hopefully avoid some merge problems
refs #6661 added a test to make sure it works
refs #6661 changed it to return an HTTP 500 code as 505 is not really correct I think
refs #6661 also return HTTP 400 when idsite is 0
refs #6661 also return a HTTP 400 in case there is another invalid request param
refs #6661 forgot to commit a file and if not suppported param is used is actually a server error not request error
Merge pull request #6671 from piwik/6661

Throw HTTP 400 error when idsite is invalid
refs #6661 added change of HTTP 400 tracker api to changelog
language update  refs #3430
Added required language name
Merge pull request #6681 from piwik/translationupdates

Added Piwik translations for Tagalog
submodule update
refs #4485 better error message in case a not yet installed plugin is required
Merge branch 'master' of github.com:piwik/piwik
fixed test