Add META.json for PGXN distribution.

[theory]

If you'd like to release it as unstable or testing, add "release_status": "unstable" or "release_status": "testing" as appropriate. Simplest way to package it up would be:

git archive --format zip --prefix=uint-0.0.1/ --output ~/Desktop/uint-0.0.1.zip master

You'll likely want to set a non-zero version in the uint.spec file (I made the version 0.0.1 in the META.json; please update as appropriate).

[theory]

Hey any interest in releasing on PGXN, @petere?

[mkgrgis]

PGXN will be usefully for this extension, but there is no reaction from @petere . Maybe there were no link to the site?