Fix unit test page

- Move debug build file from `blockly_debug.js` to `blockly_uncompressed.js` (note: requires [corresponding blockly change](https://github.com/code-dot-org/blockly/pull/779))
- Move `blockly_uncompressed` require above `goog/base` require
- Add test running instructions to README

![image](https://cloud.githubusercontent.com/assets/206973/3757650/a872e3e0-183b-11e4-8516-5f49c7b32caa.png)