Bug: add config to disable LiveDebugger (#357)

* Added `disabled` option

* Updated readme and hex docs

* Reverted docs and readme changes

* Updated variable name

Author: kraleppa

lib/live_debugger.ex

@@ -14,6 +14,12 @@ defmodule LiveDebugger do
   @assets_path "assets/live_debugger/client.js"
 
   def start(_type, _args) do
+    disabled? = Application.get_env(@app_name, :disabled?, false)
+    children = if disabled?, do: [], else: get_children()
+    Supervisor.start_link(children, strategy: :one_for_one, name: LiveDebugger.Supervisor)
+  end
+
+  defp get_children() do
     config = Application.get_all_env(@app_name)
 
     put_endpoint_config(config)
@@ -28,18 +34,15 @@ defmodule LiveDebugger do
        ]}
     ]
 
-    children =
-      if LiveDebugger.Env.unit_test?() do
-        children
-      else
-        children ++
-          [
-            {LiveDebugger.GenServers.CallbackTracingServer, []},
-            {LiveDebugger.GenServers.EtsTableServer, []}
-          ]
-      end
-
-    Supervisor.start_link(children, strategy: :one_for_one, name: LiveDebugger.Supervisor)
+    if LiveDebugger.Env.unit_test?() do
+      children
+    else
+      children ++
+        [
+          {LiveDebugger.GenServers.CallbackTracingServer, []},
+          {LiveDebugger.GenServers.EtsTableServer, []}
+        ]
+    end
   end
 
   defp default_adapter() do