Make deepPluck and deepHas work with strings

`deepPluck` and `deepHas` don't currently allow access to properties of strings. This pull request fixes that by changing the property test used.

My use case involved something like `_.max(_.deepPluck(array, 'some.deep.property.length'));`. Lo-Dash's `pluck` does work with properties of strings so this would achieve parity.

I also fixed two typos and added the minify step before `test-node` runs (I spent a long time wondering why my tests were failing because the file wasn't minified automatically). I think sometimes minification isn't complete by the time the tests start but I wasn't able to work out why.