Remove long-deprecated/unused 'debug' setting for all plugins that do
not use it.

Also deprecated the 'debug' setting for plugins that *do* use it with
encouragement to use the --debug flag.
input/collectd: Fix crash

  * The plugin would crash if an encrypted packet was received and no
    authfile was configured. This commit fixes this.
Merge pull request #996 from jordansissel/remove-unused-debug-setting

Remove long-deprecated/unused 'debug' setting for all plugins that do not use it
Merge pull request #994 from pieterlexis/fix_collectd_crash

input/collectd: Fix crash
Allow multiple GeoIP filters (fixes bug introduced in #990)

This fixes LOGSTASH-1842 by using a per-object thread-local key name.

Previously (via #990), all geoips would compete over the same
threadlocal key name :geoip. Now the threadlocal key is
'geoip-<the geoip filter object id>' which allows each instance of geoip
to use a unique key and not share with another filter instance.
Merge pull request #997 from jordansissel/fix-thread-local-geoip

Allow multiple GeoIP filters (fixes bug introduced in #990)
Move external gem requires to #register
Merge pull request #998 from jordansissel/fix-docs-building

Move external gem requires to #register
Merge git://github.com/logstash/logstash