Replace Underscore.js with Lo-Dash

Replaces Underscore with Lo-Dash because it is faster: http://lodash.com/benchmarks

`_.isArguments`, `_.isDate`, `_.isFunction`, `_.isNumber`, `_.isObject`, `_.isRegExp`:
lodash.min x 872,359 ops/sec ±4.83% (80 runs sampled)
underscore-min x 509,960 ops/sec ±0.68% (88 runs sampled)
lodash.min is 64% faster.

`_.map` iterating an array:
lodash.min x 2,035,892 ops/sec ±6.76% (85 runs sampled)
underscore-min x 802,734 ops/sec ±0.96% (86 runs sampled)
lodash.min is 140% faster.

And so on.