Create and "oss-parent" for Sakai

In researching, the oss parent is deprecated and hasn't been updated for years. [1] This is mostly used for releasing release configuration. My proposal is to move all of this release information up out of master, have master depend on a static version (released) of this artifacts which should change very infrequently.

This can also be used to more easily release other projects outside the release (like webjars) which also change infrequently.

So it would be
oss-parent->master->everything in a regular release
oss-parent->webjars

I thought about packing all of the stuff in "oss-parent" into master (most of it is there anyway) but then we have to release master and the version will be out of sync. Copy/pasting this everywhere doesn't seem great either.

This should have no real effect outside of release management.

[1] "We suggest to manage parent POM files for your own organization as needed." https://github.com/sonatype/oss-parents