Webpack

Updated to support webpack-build1.0.0. Note that webpack-build needs to be invoked with
the `-s` flag to boot the server. For example, `node_modules/.bin/webpack-build -s`.

ADDITIONS

**API**

- Added the `populate_manifest_file` function

**Settings**

- Added the `HMR` setting, which toggles support for hot module replacement
- Added the `USE_MANIFEST`, `MANIFEST`, `MANIFEST_PATH`, and `MANIFEST_SETTINGS` settings, which provide
support for offline manifests
- Added the `POLL` setting, which toggles the behaviour of webpack's file watcher in non-OSX environments
- Added the `BUILD_URL` setting, which denotes a url to an endpoint exposing webpack-build
- Added the `CONFIG_DIRS` setting, which enables lookups for relative paths to config files
- Added the `CONTEXT` setting, which denotes the default context sent to config functions
- Added the `CACHE` and `CACHE_DIR` settings, which control webpack-build's persistent file cache

**Dependencies**

- Added a dependency on the webpack-build JS package


CHANGES

**API**

- `webpack.compiler.webpack` now accepts the signature `(config_file, [context], [settings], [manifest], [compiler])`

**Settings**

- `OUTPUT_DIR` now defaults to 'webpack_assets'
- `BUNDLE_URL` is now `STATIC_URL`
- `BUNDLE_ROOT` is now `STATIC_ROOT`
- `WATCH_SOURCE_FILES` is now `WATCH`
- `WATCH_DELAY` is now `AGGREGATE_TIMEOUT`


REMOVED

**API**

- Removed the undocumented config file writer

**Settings**

- Removed the BUNDLE_DIR and CONFIG_DIR settings
- Removed the WATCH_CONFIG_FILES setting. In practice it proved to introduced memory leaks leading to
inevitable segmentation faults

**Dependencies**

- Removed the js-host dependency.
- Removed the python-js-host dependency.
- Removed the webpack-wrapper dependency.

- Python 3 fixes.

- Added a config file writer.
- The directory specified by the BUNDLE_DIR setting is now nested in another directory specified by OUTPUT_DIR.
- Added a setting CONFIG_DIR, which is nested in OUTPUT_DIR.

- Fixed an import error when configuring webpack from django.

- Renamed the project from django-webpack to python-webpack.
- The django dependency is no longer required, comparable functionality is still preserved if you choose
to use django.
- The project is now imported as `webpack`, formerly it was `django_webpack`.
- Ported the JS dependency from django-node to js-host.
- The django staticfiles helpers are now located in `webpack.django_integration`.