Select with {key: value} style options#21

This PR enables use of `key: value` style options for the `select` field. And, as a bonus, adds Coffeescript 2. ```coffeescript template = makeTemplate """ select(@value @options) """ options = Observable nap: "Napoleon" bar: "Barrack" model = options: options value: "bar" select = template model assert.equal select.value, "bar" # adding an option options Object.assign {}, options(), {test: "Test"} assert.equal select.querySelectorAll("option").length, 3 # deleting an option delete options().test options Object.assign {}, options() assert.equal select.querySelectorAll("option").length, 2 ``` Observable value ```coffeescript template = makeTemplate """ select(@value @options) """ options = Observable nap: Observable "Napoleon" bar: Observable "Barrack" model = options: options value: "bar" select = template model optionElements = select.querySelectorAll("option") assert.equal optionElements[1].textContent, "Barrack" options().bar "YOLO" assert.equal optionElements[1].textContent, "YOLO" ``` With the PR from [distri/observable](https://github.com/distri/observable/pull/6) adding and deleting option can be shorter: ```coffeescript # adding an option options.extend {test: "Test"} # deleting an option options.remove "test" ```