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 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.
Merge remote-tracking branch 'origin/pr/23'
Remove node_modules/.bin from package scripts

./node_modules/.bin won't be necessary because `npm run` appends it
to the PATH automatically.
[FIXED] `undefined | append:1` would output first filter (fixes #22)

Promise.reduce will take the first element of the array if the
accumulator is empty. And sadly the first element is the first filter.
[CHORE] Cleanup white-space in standard_filters.coffee
[PERFORMANCE] Avoid Array.join in append and prepend filters
[TEST] Test filters against plain objects
[FIX] Filters should handle objects returning non-strings in toString()
[CHORE] fix whitespace in filters.coffee
0.3.3