[SPDK] [Release] 20.07: SPDK CSI driver, new accel_fw commands, I/O abort support

On behalf of the SPDK community I'm pleased to announce the release of SPDK 20.07!

This release contains the following new features:

- SPDK CSI driver: Added CSI driver to bring SPDK to Kubernetes storage through NVMe-oF or iSCSI. Supporting dynamic volume provisioning and enabling Pods to use SPDK storage transparently. This feature is considered experimental. See https://github.com/spdk/spdk-csi repository for more details.
- Acceleration Framework: Added commands for compare, dualcast, crc32c, along with batching support for all commands in all plug-ins. See https://spdk.io/doc/accel_fw.html for detailed information.
- I/O abort: Added support for aborting I/O commands to NVMe, NVMe-oF and Bdev layers.
- Env PCI drivers: Added env APIs to provide greater flexibility in registering and accessing polled mode PCI drivers.
- RDMA library: Added `rdma` library providing an abstraction layer over different RDMA providers. Two providers available are verbs and mlx5 Direct Verbs.
- spdk_dd: Added an application for copying data to/from files and SPDK bdevs efficiently.
- bdevperf config: Added support for configuration files similar to FIO, to allow benchmarking more complex use cases. See https://spdk.io/doc/bdevperf.html for more details.
- DPDK: Added support for DPDK 20.05.

The full changelog for this release is available at:
https://github.com/spdk/spdk/releases/tag/v20.07

This release contains 842 commits from 44 authors with over 44k lines of code changed.

We'd especially like to recognize all of our first time contributors:

	Dayu Liu
	Haichao Li
	Jörg Thalheim
	Kyle Zhang
	Monica Kenguva
	Ntsaravana
	Peng Yu
	Simon A. F. Lund
	Sochin Jiang
	Sven Breuner
	Wenhua Liu
	Yibo Cai
	
Thanks to everyone for your contributions, participation, and effort!

Thanks,
Tomek