Add _.exclude(object, *keys)

Return a copy of the object, filtered to exclude the blacklisted keys (or array
of valid keys).

Similar to _.pick, but using blacklisting instead of whitelisting which can be
more appropriate in some cases.
adding a rel=canonical
adding docs about isObject
Implement mobile-site for underscore
Merge pull request #610 from hswolff/mobile-site

Implement mobile-site for underscore
initial draft of removing sparse array workarounds.
space removal typo.
removing over-indentation.
removing longstanding broken test.
alignment and variable name
breaking out the HTML escaping regex for a single pass.
elaborating comment.
removing the deprecated 'intersect' name for _.intersection
removing broken noConflict test
Fixes #603. Adds an _.zipObject() function.
removing old AMD-removal warning.
adding a warning about (lack of) sparse array support
removing needless isSorted optimization.
adding parens for clarity
hoisting out the flatten function.