Add cacheBust to scripts

closes #1977
Only selectAll if there's console content

Because this causes the entire page to be selected when it's loading :-\

Fixes #1979
Merge pull request #1982 from jsbin/fix/1979

Only selectAll if there's console content
Merge pull request #1978 from jsbin/fix/1977-cachebust-scripts

Add cacheBust to scripts
Merge branch 'master' into feature/asset-hosting
DnD upload x-browser test + paste

Note that paste has buggy implemention in browsers: it only works in Safari + Chrome (not tested IE), and onlys with image data, rather than copying a file from your desktop and pasting - if you do this, you'll upload a png of the application's icon. Stupid, yes. Broken, yes. I may decide to kill paste support, but it's fucked in the head.

Also includes API to get total size of your bucket.