Allow extraction of rsids even if some values in the field are not rsids

[talavis]

Describe the pull request:

• [ ] Bug fix
• [X] Functional change
• [ ] New feature
• [ ] Code cleanup
• [ ] Build system change
• [ ] Documentation change
• [ ] Language translation

Pull request long description:

After adding rsids using gatk, ACPop has values in the format 1:3195;rs6421780 in the rsid column. Instead of checking whether the first value starts with rs, it will now check all values in the column for rs and check whether any were found.