Cache the _fetchResources promise
Rename Env methods to more descriptive ones
Rename ctx.format to ctx.formatValue and ctx.get to ctx.formatEntity
Use new method names in runtime bindings
Fix linting error
Merge branch 'newapi' into immutable

Conflicts:
	bindings/l20n/runtime.js
	lib/l20n/context.js
	lib/l20n/env.js
	tests/lib/context/fallback_test.js
	tests/lib/context/lifecycle_test.js
	tests/lib/context/resources_test.js
	tests/lib/env/events_test.js
	tests/lib/env/langs_test.js