Updating changelog
allow empty strings for partition keys and row keys
Making errors instance of Error()
Updates for coding style
Merge pull request #317 from christav/fixing_error

Making errors instance of Error()
For stream output, invoke callback on response
Merge pull request #320 from pofallon/dev

In case of inputStream, invoke callback on response event
#325: need to change dependency to keep xml2js 0.1.x or update code to deal with 0.2.x.
Changing dependency.
Safe array enumeration by using forEach method.
Enumerating all object properties is error prone and may pick up properties that are not array indexes.
one more array enumeration in this file
Merge remote-tracking branch 'upstream/dev' into dev
Updating serviceclient to call callback when finished.
Adding event emitter.
Adding UT.
Making sure readable stream is open before piping.
Adding error handling.
Correcting typo.
Renaming variable for consistency.
Setting default proxy protocol.