--exclude flag to explicitly exclude libs from build

[rvagg]

Mainly for use where you want to exclude deps from libs from being included in your build. Could come in handy for libs that have extra Node deps that don't need to be in the browser but the specific example I'm thinking of is where you may want to switch out one lib for another compatible lib: Underscore & Lo-Dash being the prime example.

$ ender build jeesh reqwest backbone lodash --exclude underscore

(the only way to achieve this at the moment is to set up a local backbone clone with a package.json that doesn't have underscore and build with ender build jeesh reqwest /path/to/backbone lodash)

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