Fixing travis for 3.1 builds
Fix composer and travis to framework 3.1
Merge pull request #158 from tractorcow/pulls/0.5/compat

Fix composer and travis to framework 3.1
Update translations
Fixes #135: LeftAndMain switching between subsites

When trying to switch to a different subsite from a page's editing view, it wouldn't switch. This was partly due to a $record always existing due to the homepage fallback on currentPageID : https://github.com/silverstripe/silverstripe-cms/blob/3.1/code/controllers/CMSMain.php#L816

So as currentPage() couldn't actually be used to test for the existance of a current page, I've added in a check for isset($this->owner->urlParams['ID']).

I've also moved the check for $_GET['SubsiteID’] which indicated a forced subsite switch (eg. via the dropdown switcher) above the check for a current page, as it should take precedence, and it wasn't being run when both conditions matched causing the subsite not to change.

Tested changing subsites from /admin/pages, from page edit view, from a page edit URL, and from other CMS sections such as Files and Security, and all seems to be working perfectly now.
redirect fix between CMS sections

Previously if you're in settings and change subsite, it always redirected you to /admin/pages which was quite annoying. Now it persists the page you're on.