* Updates per review comments
1) core_uploader service waits for syslog.service
2) core_uploader service enabled for restart on failure
3) Use mtime instead of file size + ample time to be robust.
* Avoid reloading already uploaded file, by marking the names with a prefix.
* Updated failing path.
1) If rc file is missing or required data missing, it periodically logs error in forever loop.
2) If upload fails, retry every hour with a error log, forever.
* Fix few bugs
* The binary update_json.py will come from sonic-utilities.
* Corefile uploader service
1) A service is added to watch /var/core and upload to Azure storage
2) The service is disabled on boot. One may enable explicitly.
3) The .rc file to be updated with acct credentials and http proxy to use.
4) If service is enabled with no credentials, it would sleep, with periodic log messages
5) For any update in .rc, the service has to be restarted to take effect.
* Remove rw permission for .rc file for group & others.
* Changes per review comments.
Re-ordered .rc file per JSON.dump order.
Added a script to enable partial update of .rc, which HWProxy would use to add acct key.
* Azure storage upload requires python module futures, hence added it to install list.
* Removed trailing spaces.
* A mistake in name corrected.
Copy the .rc updater script to /usr/bin.
