Implement NCBI's tools from SRA Toolkit

NCBI's Trace Archive data is only available in SRA format now.

NCBI offers downloadable tools to convert these files to FASTQ and other formats on local machines, but it would be ideal if the galaxy would accept SRA input and we had the tools implemented from NCBI's SRA Toolkit: NCBI SRA Handbook

High priority tools: fastq-dump, sff-dump