Add more standard filters

- capitalize
- sort
- map
- escape
- escape_once
- strip_html
- strip_newlines
- newline_to_br
- replace
- replace_first
- remove
- remove_first

date is not added yet. Could you take [the code in darko](https://github.com/dotnil/darko/blob/master/lib/liquid/index.coffee) a look and
tell me if that date filter implementation suits the need of
liquid-node or not?

If positive, I'll put the date filter together also.

References:
- https://github.com/Shopify/liquid/wiki/Liquid-for-Designers
- https://github.com/Shopify/liquid/blob/master/lib/liquid/standardfilters.rb
- https://github.com/Shopify/liquid/blob/master/test/integration/standard_filter_test.rb