Some README.md edits

Just some things I noticed when attempting to try out the InlineGUI plugin in my project.

1. Changed the 'property' options in the Eco template snippet to 'attribute' options, as you yourself have in the Inline GUI skeleton you're making.  This allows the rendered divs to produce 'property' attributes without "undefined" when using Jade and text-pluginto render Eco.  If "property" works in straight Eco then ignore this.

2. Maybe I'm using InlineGUI wrong but going to localhost:9778/inlinegui never works for me, I always get "Not Found" and that's it.

This is basically my first proposal for a file change on GitHub in my entire life, if I'm out of line or not doing this right please let me know!