Create set of small test files

For time- and resource-efficient automatic integration testing of the workflow on the testing VM, a set of small input files is required, replacing the current set available in tests/test_integration_workflow, which takes up more than 80 Mb. Specifically, the following files are needed:

• a reference sequence <100kb, e.g., an artificial chromosome or fragment of actual chromosome
• a gene annotation file with at least one gene entry, two transcripts and multiple exons for that chromosome region
• a "synthetic" paired-end RNA-seq library in FASTQ format (10 to 1000 reads); the library should follow naming conventions for paired-end libraries such that only the first mate sequence can be used for workflow sections tailored for single-end libraries
• a "ground truth" file with the reference sequence coordinates that each read originates from and the gene that it overlaps with, if any

The following changes are required to update the integration test:

• sample table file and workflow configuration have to be adapted for new file names, if applicable
• md5 sums for expected output files have to be updated