v0.5.1

• Reverted the removal of bootstrap.js since we're actually using three of the plugins there (popover and tooltip for chart descriptions and dropdown for our button layout)
• Cleaned up the way we rely on bootstrap.css, by overriding a few selectors in metrics-graphics.css and using the hosted version of bootstrap.css for everything else

These changes ensure that our library remains modular and doesn't mess up people's websites if it so happens that they have bootstrap installed.