Rework gitignore by combining all gitignore files and adding files
generated by running tests.
Signed-off-by: Felix Matouschek <fmatouschek@redhat.com>
Ignore additional files we do not want to be part of the released
collection. Also ignore build artifacts in .gitignore.
Signed-off-by: Felix Matouschek <fmatouschek@redhat.com>