Release 1.7.2

The new release 1.7.2 has some small changes only:

• The flex output now allows tables with only the id column (or columns).
• The osm2pgsql-replication script now always expects the osm2pgsql binary to be in same path as itself.
• Adds the flag --middle-schema=SCHEMA to the osm2pgsql-replication script which allows placing the replication status table in a schema other than PUBLIC (Thanks to @JakobMiksch).
• More tests have been converted to the new BDD format.
• Various code cleanups and refactorings especially in the expire code.