Do a HEAD request on URLs to check if the exist. Fixes #111.
Made URL validation work with gdocs URLs. Issue #111.
Trivial cleanup
Added a comment about setCustomValidity()
[#116,views/load][s]: dataset.name is now dataset.id in import and do basics for url-usability - fixes #116.
Moved preview pane onto import page
Rearranged the import tabs
Clear preview pane before adding a new one
Because slickgrid takes measurements of its container, make sure it's in the DOM before calling render().
Added some explanatory text.
Fixed dashboard sorting issue. Fixes #107.
Fixed project deletion.
Merge branch 'master' into gh-pages