Fix typo in comment.
Added GeoIP test files to .gitignore.
Fixes #3619, add reports by dimension section to Referrers overview.

Notes:
  - fix bug in last #3619 commit that broke referrers overview page.
We now use a testing matrix that matches three PHP versions
and three testsuites together.

refs #3722
Merge branch 'master' of https://github.com/piwik/piwik
Change pwd, enable text coverage (HTML report is no use)

Adjust travis.sh

refs #3722
Merge remote-tracking branch 'upstream/master' into svg-map-widget