Ported the library to use View-subclasses

The library now consists of 3 View-subclasses that can be composed to form the same messages as the old could - but getting rid of all the jQuery-HTML-building.
All content is built using the Atom 'content'-DSL now.
Relocate each class to individual files.

Each class now has its own file in the lib/ directory. The inherits-function has been moved to a utils-file.
Validated files with JSLint.

The three classes now all satisfy the JSLint criteria. The inherits-function from lib/utils.js does not, but for compatability with CoffeeScript I haven't modified it to satisfy JSLint.
Call `View`-constructor with arguments

The `View`-constructor wasn't being called with the arguments it should have been called with.
This made `content` not receive the parameters it should have.
Use `initialize` instead of `afterAttach`

Moved the invokation of the `View`-constructor, which allowed the use of
`initialize` instead of `afterAttach`
Ensured that detach/attach works.

Removed custom implementation of , and added a  method that is rigged to the close-button.
Reset the messages-property when clearing.
Removed unnecessary close method.

The  method was not needed. It was equivalent to  anyway.
Added  back to MessagePanelView.
Merge pull request #1 from fangel/master

Port the library to use View-subclasses?