fix stdin message handling & specs

closes #1386
Pass correct HOME env into chroot

Without this patch the logstash isn't able to start on Debian 7 when using file input, as both HOME and SINCEDB_DIR aren't set in chroot.
Merge branch 'pr/1343'
closes #1343
initial spec for pipe input

removed logging

fixed encoding header

closes 1385
Merge git://github.com/logstash/logstash