Support v3.x DDN Firmware

DDN changed the format for the latency data in their 3.x firmware. This release includes code to handle that change.

A few notes regarding the changes:

• The change to support v3.x firmwares requires changes to the SQL database schema (and InfluxDB fields, if you're using InfluxDB), so make sure you specify the -i parameter to initialize the database(s) the first time DDNTool is started after the firmware update.
• One instance of DDNTool can support DDN's with either 3.x or 2.x firmware, but don't try to use the same instance to connect to DDN's running mixed versions.

Support RHEL7

Adds support for RHEL7 packages: bdist_rpm will include a systemd script for startup/shutdown rather than an upstart script. Other features / bugfixes / cleanups:

• InfluxDB support is now optional. If output to an InfluxDB server is NOT enabled in the config file, then DDNTool will continue run even if the Influx python modules can't be loaded.
• If the config file can't be parsed, the code will throw an exception with a meaningful message now
• Various minor code clean-ups

Support InfluxDB

Adds support for writing data to InfluxDB. Existing support for output to MySQL is unchanged. The tool can write to either, or both simultaneously.

Auto-reconnect when a DDN controller reboots

Adds code to automatically restart a subprocess and reconnect to a DDN controller. Useful for when controllers are rebooted after firmware updates or similar.

Also fixes the RPM building code on RHEL6.

Fix syslog bug

2.1 couldn't log to the syslog because of a missing import. This release fixes that.

Version 2.1

Adds read & write bandwidth values and separates the raw counts into a new table (LunInfoRaw). The calculated averages remain in the LunInfo table.

Requires a 2.3.x version of the DDN firmware.