Cohabitation with LiveView

Since LiveView is now public, probably the developers will try to use both libraries in the same app, but at this time it is not possible because `Drab.Client.generate_drab_js/3` rises when it tries to get the controller module for a `LV` page, as `:phoenix_controller` is not present in the `conn` of a LiveView page.

Checking for the presence of `:live_view_module` in the `conn` parameters reveals if the page is suited or not for generating the drab js, for example:

```elixir
defp generate_drab_js(conn, connect?, assigns) do

if !conn.assigns[:live_view_module] do
controller = Phoenix.Controller.controller_module(conn)
...
```

This way both libraries can cohabit at the same time in the same app, using Drab only for pages based on Controllers/.eex templates (but not for LiveView pages because its js code will not be injected).

Edit:
The PR #192 solve this problem with a more general solution than the one initially proposed above

Start at Drab.Client.generate_drab_js/3 and inspect how LiveView connections differ from controller-backed pages, especially the :live_view_module and :phoenix_controller values. Review PR #192, which the issue says provides a more general solution, and verify that Drab and LiveView can coexist without injecting Drab JavaScript into LiveView pages.

Written by the indexing model from the issue text.