Remove DNA_with_more_gaps

Sadly, removing something with a *really* cool name...
Remove remaining IUPAC_DNA_ambiguities references
Import from skbio instad of pycogent

This will depend on brokit, so wait on the merge of brokit modules that
@josenavas is working on
address @ElDeveloper's highly useful comments
Merge pull request #1429 from ElBrogrammer/iupac_dna_ambiguities

Remove DNA_with_more_gaps
Merge pull request #1432 from adamrp/skbio_app_util

Import from skbio instad of pycogent
Remove unused imports of unzip

This function was not being used anywhere in these modules.
Merge pull request #1437 from ElDeveloper/remove-unzip-usage

Remove unused imports of unzip