Add splunk adapter as a sub-module. (Code is copied from splunk repository as of https://github.com/julianhyde/optiq-splunk/commit/3ea93dc8382530048e95d9070ada4b034786fe3e.)
Fix maven web site, http://www.hydromatic.net/optiq.
Disable spark for release.
[maven-release-plugin] prepare release optiq-parent-0.4.12