CodeMirror and multiple views skeleton

Changes are mostly described in commit 87f5fd0

and in issue #34 *[comment](https://github.com/silverwind/droppy/issues/34#issuecomment-35849411)*


![image](https://f.cloud.github.com/assets/2925395/2242544/79efe0b4-9d06-11e3-8b4a-7164c852d2ee.png)