Merge pull request #894 from WindowsAzure/release-0.7.1

Release 0.7.1
Merge pull request #919 from guangyang/release-0.7.1

update changelog and readme for release 0.7.1
Merge branch 'master' of https://github.com/WindowsAzure/azure-sdk-tools-xplat into release-0.7.1