Updating package.json, readme, and changelog
Merge pull request #755 from christav/release-0.7.3

Updating package.json, readme, and changelog
Merge pull request #757 from WindowsAzure/release-0.7.3

Merge Release 0.7.3 into master
Merge pull request #758 from WindowsAzure/master

Merging release 0.7.3 from master to dev
First round adding HDInsight service