API: dot correctness

API: dot correctness

From and to API consumers we'll now always require/send names (and
content) with dots. To the backend, we'll always require/send without
dots. Some API tests now check the data written to the sqlite DB, too.

Incoming names are now checked against a restricted list of chars,
fixing #1437. The double dot case is taken care of by DNSName (and
we'll no longer report an ISE if DNSName parsing fails - we make
sure to parse all names in a try/except).

Cleanup leftovers from pre-DNSName times.

Turn auth api tests back on in travis.