v2: Content-Type header is required to be application/jose+json, so we use Requests python library to mange all HTTP requests simply

v2: acme-dns-tiny: enlarge exception except to DNSException as we can receive either NoAnswer or NXDOMAIN

v2: acme-dns-tiny: if a CNAME is defined on _acme-challenge.example.org following it to decide where to install the TXT records

Limitation: it only follows one CNAME for the moment, maybe we should
go through CNAME chain, but it will requires to detect CNAME loop too.

acme-dns-tiny: only wait for 1 TTL by domain and be more accurate for the TTL configuration documentation

Fix invalid txt record errors

See merge request !11

The new option TTL is used to configure the TXT resource records installed
by acme-dns-tiny: this allows us to correctly define records according
to the DNS server policy.

It allows too to fix issues about invalid TXT record errors, caused by
the ACME server cache which hidden new TXT records to the ACME server.

v2: allwo to define CSR file path by argument

See merge request !10

acme-dns-tiny: fix the way to override ConfigParser values and add test in main process for the csr option

acme-dns-tiny: add a wait delay just before real check server to be sure that ACME DNS entries are updated

This workaround this issue: when starting this test after the two others, ACME staging server seems to have again in cache some TXT record and return error to get certificate.
As this test just use acme-dns-tiny to register the account key, we just check the registration is working.

remove all tests workaround: timing workaround is already available with the "CheckChallengeDelay" form the configuration.