Topic/replace tabs js

JavaScript for steroids.tabBar.replace.

Possibly native issues:

- In testApp tabBar -> "Start replace tabs repeating test" causes segmentation fault which crashes Scanner
![organizer_-_devices](https://cloud.githubusercontent.com/assets/1540411/3200336/1e5e664c-ed7b-11e3-8d38-15795a304bc8.png)

- Calling `replace` with malformed options object crashes Scanner
![organizer_-_devices_and_topic_replace_tabs_js_by_sampax__pull_request__86__appgyver_steroids-js](https://cloud.githubusercontent.com/assets/1540411/3200318/d554d954-ed7a-11e3-8994-0f8cd3b93328.png)
 
- Position property in `replace` options doesn't do anything (functionality inferred from old tests, not sure if correct assumption)
- Replaced tabs are not unloaded from memory (see Safari debugger)