Added packages_dev.xml with all third-party packages used for development and unit test environment

Change-Id: Ie3e3ed44e2f86c8ed7e801b598740cd86a34892d
Addded support for specifying <packages.xml> file path while running
fetch_packages.py script as we are maintaining dev dependencies in a
seaprate packages_dev.xml
Change-Id: If518024835c59705098c9dd4a1b5d1dd4971464e
Merge "Addded support for specifying <packages.xml> file path while running fetch_packages.py script as we are maintaining dev dependencies in a seaprate packages_dev.xml Change-Id: If518024835c59705098c9dd4a1b5d1dd4971464e"
Merge pull request #3 from Juniper/master

Pull changes from Juniper/third-party to absingla/third-party