Canonicalize all host names

This is motivated by the Spark/Tachyon integration, where Spark requires
the host names for all block locations to match precisely with its view
of the universe. Since Spark does canonicalize all of its host names, it
seems reasonable for us to do so as well.
Downgrade "Master disconnected" log message to DEBUG level

This is particularly annoying during interactive shell sessions (e.g.,
spark-shell) where periods of not using Tachyon will visually interrupt
user input.
Merge pull request #217 from aarondav/fixes

Downgrade "Master disconnected" log message to DEBUG level
code format for NEtworkUtils.java
Merge pull request #216 from aarondav/canonicalAddress

Canonicalize all host names