Removed hard tabs in libprocess.

From: Niklas Nielsen <nik@qni.dk>
Review: https://reviews.apache.org/r/14720
Removed hard tabs in zookeeper related code.

From: Niklas Nielsen <nik@qni.dk>
Review: https://reviews.apache.org/r/14721
Removed hard tabs in the Mesos code.

From: Niklas Nielsen <nik@qni.dk>
Review: https://reviews.apache.org/r/14722