Update grammar mappings

- [x] Sort grammars
- [x] Update mapping in grammars.coffee to separate command/args for each type of execution
- [x] Accommodate the change in script-view.coffee
- [x] Add "selection based" support for Haskell
- [x] Add "selection based" support for RSpec
- [x] Update README.md

---

I implemented some changes to `grammars.coffee`'s layout as [discussed on](https://github.com/rgbkrk/atom-script/pull/95#issuecomment-40210787) #95.
>One of the other languages was hoping for that too. We'd need to re-think/revise how we do `language -> command, args` mappings.
>
>This would be redundant for some other languages but we could switch to a structure like this:
>
>  ```RSpec:
>    "Selection Based":
>      command: "ruby" # Just an example
>      args: (code) -> ['-e', code]
>    "File Based":
>      command: "rspec"
>      args: (filename) -> [filename]```