Tabbing in the modal is not self contained

[fauverism]

After opening the modal window and hitting tab you are brought to the OK btn, then Cancel btn then after clicking a 3rd time the url bar has the focus. Continuing hitting tab will rotate thru the tabindex on the page.

This behavior is not present in the native Twitter Bootstrap. In the native Twitter Bootstrap you are able to hit tab repeatedly, with a modal open, and rotate thru the tabindex in the modal. The focus does not leave the modal window.

[pkozlowski-opensource]

Yes, this is dupe of #738