add sort filter
filters: date: add target option

Update the date filter to support a target option.  If defined,
instead of updating the @timestamp field, update the given target field.
This is useful for events that have multiple timestamps (e.g., start and
end times).
- Check for EOF condition (remote has closed) before writing.

If we don't do this, then the write will still succeed even after the
remote has closed (half-closed in CLOSE_WAIT on our side), and the 2nd
write after will fail causing the previous event to be lost.
- Try forever to connect w/ exponential backoff
- remove a blank line
remove old event shims and fix any uses of it
remove commented code
Fix some typos in CHANGELOG.
Merge pull request #663 from bernd/changelog-typos

Fix some typos in CHANGELOG
add test case, found some issue and fixed them.
Allow empty plugin sections again.

This used to work with 1.1.x.

See: https://logstash.jira.com/browse/LOGSTASH-1344
Merge pull request #664 from bernd/LOGSTASH-1344

Allow empty plugin sections again (LOGSTASH-1344)
Merge pull request #625 from jdve/date-overwrite

filters: date: add target option
fix encode (output) for oldlogstashjson codec.

It was referencing the obj variable which didn't exist
1) adjust the comments
2) change milestone to 1
3) add comments for the ignored case.
Merge pull request #609 from fbird/master

add sort filter
add coverage
Update walkthrough conf files to reflect 1.2.x syntax changes
make comment clearer
Merge pull request #667 from logstash/doc-fix

Update walkthrough conf files to reflect 1.2.x syntax changes