Character set checking for few of ASN.1 strings.
Reduce DNS test noise (fixes #242).
Added entries queue size limit.
Add tools to dump logged certificates and STHs.

They are rather basic for now, but are useful when debugging servers using
the FileDB storage.
Fixed IPAdress error message.
Catch invalid input early on in AsyncLogClient::GetEntries.
Moved apt-get python packages to pip (travis).
Store (and use) entries in database.
Added ASN1IllegalCharacter exception.
Storing entries no longer break client.
Really wait until the server has started.