Test Illumina cutadapt support for ITS and dovetailing primer pairs, strictness of primer matches

[cjfields]

Per #56, we need to test:

1. Strictness of primer matches for paired-end and single-end data (e.g. requiring 5' primers be present)
2. Dealing with 3' primers from dovetailing or variable-length amplicon pairs like CO1 or ITS

[cjfields]

Stupid autocorrect