Change resourceUri to a text input

When using longer resource links, the resourceUri `<code>` block flows
outside of the runner div and lays over the top of the docs. I’ve
changed the resourceUri to be a text input, monospace formatted, with a
select() onclick to make it easier to read the URL, and really simple
to select it and run it in a browser.

**Original interface with overflow**
![originalui](https://cloud.githubusercontent.com/assets/44993/3983091/ba04b2f4-287c-11e4-8b0c-829e7ac02c2f.png)

**New interface with text input**
![newui](https://cloud.githubusercontent.com/assets/44993/3983118/eb8abfd0-287c-11e4-87c2-f95bd7e4fa3f.png)