Allow bundles to provide settings of their own.
Update Resolver API to receive context.
Write some comments for the resolver classes.
Move the resolver attribute to a proper config value.

This does not change the API, but makes it easier to set for bundles via the
existing constructor arguments.
Support bundle config settings in YAML loader.
ContextWrapper: Fix environment property, add get().
Fix some missing context wraps.
Update Jinja2 template tag for new syntax.
Make Filter class use context correctly.
Fix some comment grammar.
Script module had some issues with new API still.
Merge branch 'master' into feature/settings-tree

Conflicts:
	src/webassets/bundle.py
Merge remote-tracking branch 'origin/feature/settings-tree' into feature/settings-tree
Merge branch 'feature/settings-tree'
Move resolver change not to dev version section.

Was auto-merged incorrectly.