Add site logo theme support to bundled themes

[bschneidewind]

This picks up where @narenin was at and addresses the twenty-ten, twenty-eleven and twenty-twelve themes.

Twenty-Thirteen and Twenty-Fourteen need to be discussed further before moving forward with any development:
1 - Twenty-Thirteen currently has the anchor tag wrapping the linked text and the site description. This should be updated so that the anchor tag lives inside the h1 and the h2/description is not linked at all.
2 - Twenty-Fourteen may not be suitable for a logo due to the size limitations of the logo area on this theme.

Trac ticket: https://core.trac.wordpress.org/ticket/61766

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Props narenin, bschneidewind.

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