ev3dev-stretch R2 Release Candidate

We have a new stable release candidate ready for testing. Be a pal and try it out.

Download snapshot-ev3dev-stretch-ev3-generic-2019-09-08.img.xz from here.

Changes since ev3dev-stretch R1:

• Updated to Debian 9.9
• Improved Bluetooth availability #925
• Updated ev3dev-lang-python and ev3dev-lang-java libraries.
• A few small Linux kernel driver fixes

If all goes well, this will become the new main download in a few weeks.