Adapted data import progress bar to Bootstrap 3.
Adapted sidebar to Bootstrap 3.
Removed redundant id attribute and cleaned up another html attribute.
Use data- attributes to open the data import popup, instead of doing it with javascript code.
Bottom margin removed from alerts.

The "margin-bottom: 20px" property in alerts was like an invisible "band" that stopped the user from clicking on buttons even though they were visible below the alert. Less confusing this way.
Open the new folder popup using data- attributes instead of javascript code.