Remove all 0.1.1-xxx pre-releases.

[schmidtw]

To reduce the clutter, we are going to remove all the pre-releases in the 0.1.1 series except the formal 0.1.1 release on or after June 22, 2018.

Please comment here if they are needed.

Going forward only the official releases will be kept.

[joe94]

@kcajmagic has a script to delete releases. Perhaps, we should modify the script to remove those with the prefix in this^ title.