mpileup:

- Fetch samtools version
- optionally run bcftools (as per --help)
mpileup:

- bcftools handling
- command line arguments
Fix bcftools command
mpileup:

- Default setting for bcftools is 'view -Ov' - Always give VCF output
- Some help text
Only bcftools with -Ov is supported
mpileup: Added comment
Merge pull request #90 from pjotrp/master

mpileup should be functional and ready for testing