Studio - Make build list scrollable

[newgene]

In the builds tab, when the build list grows longer and longer, it will push the two buttons down and disappear from the current view.

Suggest making the build list scrollable, make the two buttons also viewable on the screen. Also we should add the "Create New Build" button to the main panel, somewhere on the top panel.

[newgene]

Probably need to do the same for "Sources" and "API" tabs.