add dump filter documentation

added changelog update

Fix mobile viewport (meta) (mozilla#865)

closes mozilla#860

Order builtin filters alphabetically (mozilla#863)

Ordered filters alphabetically in English and French documentation.
Chinese docs only have references to Jinja docs, so are not updated.

Closes mozilla#858

added more elaborate tests and adding variants of values that can be passed in json

remove single quotes and added spaces here and there

change foo dump to items dump consistency

change key types

correcting documentation dump filter

perfecting dump documentation

perfecting dump testing

added different indentation

complete tests

… in docs/templating.md