Plan:

1. Build qbat2-base and push it
2. Build image with jhbuild
  2.1. Checkout qtwebkit
  2.2. md5sum of jhbuildrc, jhbuild.modules, jhbuild-qt-5.4.modules ("jhbuild*"?)
       -  I think best option is to calculate hash of uncompressed tar file with all subject files
  2.3. If qbat2:$hash already exist, goto 3
  2.4. Run build-jhbuild.sh in docker with mounted WebKit
  2.5. Save DependenciesQT inside container fs instead of mounted
  2.6. Push result as qbat2:$hash and qbat2:latest
3. Build qtwebkit
  3.1. Start qbat2:$hash with mounted WebKit
  3.2. Move DependenciesQT to WebKitBuild
  3.3. build-qtwebkit-release.sh