runtime: bump version to v0.12-DEV

Gerbil-v0.11

Gerbil-v0.10

Gerbil-v0.9

ChangeLog: better description of changes for v0.8.2

Gerbil v0.8.1

Gerbil v0.8

Gerbil v0.7

Gerbil v0.6.1

Gerbil-v0.6