OS Patching Extension New Features & Unittest & Bugfixing

New Features: split scheduled/one-off patching into 2 stages; add stop operation; add rebootAfterPatch parameter

Bugfixing:
    one-off timeout
    Oracle Linux won't reboot because perl not installed
    OSPatching apt-get -y install update-notifier-common failed
    OSPatching ubuntu update package postfix failed and hang
    OSPatching opensuse_13.1 zypper refresh report error
    pakage_download_path not exists
    package_download_path not including failed pkg in one-off patch
    Failed to update 4 packages on Oracle-Linux-6 because missing dependencies
    ubuntu update package waagent failed