Bug 925216: Add media info display to Gallery; change styles in Video to match

add 1rem more padding on the left for dt and dd elements
Merge pull request #14481 from davidflanagan/bug925216

Bug 925216: Add media info display to Gallery; change styles in Video to match r=pdahiya
Bug 947107 - [Gallery] Update gallery to use new 1.3 tool bar and tab bars