Ignore all libmaxminddb-* files & dirs
Move maxmind-db to t/maxmind-db

This eliminates the need to special case it for inclusion in the tarball
Fix tests for latest test data
I gave up on distcheck and made a safedist target instead
Add note about make safedist to README.md
Merge pull request #23 from maxmind/dave/make-distcheck-work

Add a safedist make target that checks that the tarball is good