Remove double scroll bars from Clover panel.

The Clover HTML report is currently displayed in an iframe, which causes double scroll bars to display if the window is not the correct height.

The solution to remove the double scroll bars appears to be:

• add a proper floating footer to Bamboo - example
• set the height of the iframe of containing the Clover pages to the height of the available content space. Basically use JavaScript to subtract the offset.top of the iframe from the offset.top of the footer and tell the iframe to be this tall. Accommodation needs to be made for any intrusive padding in the page.
• if the window is resized, adjust the height of the iframe accordingly.

This is a similar approach to how the Crucible review UI works.

BAM-4479 has been created for the changes required in bamboo core.