Fix s/fastafile/subject introduced in "replace commonly used pattern with macros".

In commit 59f77a8ea2b6bfd6120db3738edecdf29f017f27 the
input_conditional_nucleotide_db macro changed 'fastafile' param to
'subject'.
Rename test-data/dustmasker_three_human.asn1-binary to use specific
extension.
Add test for dustmasker with maskinfo ASN.1 text as output format.
Mention makeblastdb in help.
Update READMEs, TravisCI and make_ncbi_blast_plus.sh