Merge pull request #114 from brainstorm/master

Bowtie2 site-specific tweaks for fastq_screen with Bowtie2
Merge pull request #115 from brainstorm/master

Add an extra cleanup at the end of the test, bowtie1 results got overriden by bowtie2
Merge branch 'master' of https://github.com/SciLifeLab/facs
Adding provenance JSON attributes for bowtie1 and bowtie2 in fastq_screen