[ticket/179] Correctly redirect to app.php/portal using styleswitcher

Fixed #179
Merge pull request #180 from marc1706/ticket/179

[ticket/179] Correctly redirect to app.php/portal using styleswitcher
[ticket/181] Redirect to portal by default

Fixed #181
Merge pull request #182 from marc1706/ticket/181

[ticket/181] Redirect to portal by default
[ticket/181] Add functional tests for portal redirect
[ticket/181] Check if mod_rewrite is enabled in functional tests
[ticket/181] Correctly check if Board3 Portal extension is disabled
Merge pull request #183 from marc1706/ticket/181

[ticket/181] Add functional tests for portal redirect