Add datanode-reading commands: text, tail, copyToLocal, getmerge, get, cat
Merge pull request #22 from gbadiali/master

Add datanode-reading commands: text, tail, copyToLocal, getmerge, get, cat
Fix bug with CRC32

Change-Id: I4496a430aa958a3934f8241f80d62b171bebe4e3
Updated docs

Change-Id: I121f46556f3e04a63f66549ad21c85576d6d1a03
Updated docs

Change-Id: Ideacddcfd428a94b34a9fc06da3d59f43a38ca3c
* namenode parameter should be a string
* added a default port of 8020
* corrected tests