Grok does create field when pattern matches all message

As of today grok filter does not create a specific field
if the grok matches the whole message. This commit changes
this behavior and make grok create the required field in
the configuration file
add alternative tags on grokparsefailure
@message was missing in event, added 'Message' field to @message.
- Add imap input prototype
  Tested works against gmail's imap servers.
Remove extra 'end' from redis output
Update redis.rb

@piavlo -
"actually this line
@congestion_check_time = Time.now.to_i
should come after the while loop and not before
mind adding this change to this PR?"
Merge pull request #434 from sr-ix/master

Remove extra 'end' from Redis output
Minor doc fix.

--filterworkers instead of --filterworks.
Merge pull request #435 from happymcplaksin/flagsdocnit

Minor doc fix.
- only load libraries when necessary (openssl takes 6-seconds to
  60-seconds to require 'openssl' in some cases)
- add update-flatjar target
- make update-jar target invoke a few other steps
- update jruby-openssl
- try to make monkeypatching more obvious and contained
- add locales/en.yml to the jar builds
- don't bother doing 'jar i' anymore, JRuby doesn't even look at the
  manifest index. Just wastes time during the build :)
Fix regression
- Fix quoting (which is breaking the test)
jruby 1.7.3
- bump lumberjack
- add debug monkeypatching
- add lumberjack2 input (tentative name)
- Make an attempt to work around a bug where jruby-win32ole fails to
  load because the racob dll it wants to load is in the jar file.
  Work around: Extract it and use the extracted path.