**- Why I did it**
Align style with slightly modified PEP8 standards (extend maximum line length to 120 chars). This will also help in the transition to Python 3, where it is more strict about whitespace, plus it helps unify style among the SONiC codebase. Will tackle other directories in separate PRs.
**- How I did it**
Using `autopep8 --in-place --max-line-length 120` and some manual tweaks.
Fix 259 alerts reported by the LGTM tool:
- 245 for Unused import
- 7 for Testing equality to None
- 5 for Duplicate key in dict literal
- 1 for Module is imported more than once
- 1 for Unused local variable
- Convert core_uploader.py script to Python 3
- Use logger from sonic-py-common for uniform logging
- Reorganize imports alphabetically per PEP8 standard
- Two blank lines precede functions per PEP8 standard
- Remove unnecessary global variable declarations
* 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.
