Docker: minimize build context when building Docker Images

[bschmalhofer]

Just a small optimization. Not all images need the full otobo dir as build context.

[bschmalhofer]

It looks like the build context can't be set for the automated builds Docker Hub. A possible workaround is to add lookup table in hooks/build. Currently the build context is hardcoded as '.' in that script.

[bschmalhofer]

The build context can be set in the automated build GUI. For some reason I must have overlooked it. That setting is available as $BUILD_PATH in hooks/build.
I adapted hooks/build such that the build context no longer is hardcoded to ".". Setting the build context to "/" indicating the git checkout dir is still supported.

The idea is to backport this to rel-10_0, as the directory structure hasn't really changed. The only thing to keep in mind is that hooks/build must be updated when an automated build from before 10.0.12 is needed.

[bschmalhofer]

Minimised the build context:

• nginx, nginx-kerberos: scripts/nginx
• elasticsearch: _scripts/elasticsearch . actually an empty directory
• selenium: scripts/test/sample

[bschmalhofer]

Ran the test suite, with activated Elasticsearch, with the devel-rel-10_0 images taken from hub.docker.com. The test results looked fine. Closing this issue.