Refactor extension to webpack

This change is the biggest in the history of the project. The entire
project has been refactored so it is built with webpack.

This involves:
- Creating webpack and npm config files.
- Fixing some bugs in the code due to the fact that webpack uses strict
- Merging some pieces of code which were shared throughout the codebase
(not exhaustive, more work should be done in this direction).
- Splitting the console_inject.js file into separate files (it had 1000+
- Adapting all the build-related files (Makefile, bash scripts, etc.)
- Changing the docs to explain the new build process.
- Changing the Zuul playbook/roles to adapt to the new build process.

Change-Id: I16476d47825461c3a318b3f1a1eddb06b2df2e89
diff --git a/roles/build-extension/defaults/main.yaml b/roles/build-extension/defaults/main.yaml
new file mode 100644
index 0000000..2774de6
--- /dev/null
+++ b/roles/build-extension/defaults/main.yaml
@@ -0,0 +1 @@
+make_target: chromium_stable
diff --git a/roles/build-extension/tasks/main.yaml b/roles/build-extension/tasks/main.yaml
new file mode 100644
index 0000000..7759c47
--- /dev/null
+++ b/roles/build-extension/tasks/main.yaml
@@ -0,0 +1,6 @@
+- name: Build extension
+  make:
+    chdir: "{{ zuul.project.src_dir }}"
+    target: "{{ make_target }}"
+  environment:
+    PATH: /usr/local/go/bin:{{ ansible_env.PATH }}