Make vcf_filter module compatible with indels in VCF

[Jiu9Shen]

All vcf files on Knowpulse VCF bulk loader are filtered to remove all indels now, but we need to include them in the future.
To-do list:
Check code to make sure we don't accidentally filter indels when we use vcftools at first.
Then, check all scripts of different export formats we have in the module to make sure indels can be delt properly.
At last, test different formatted export files if they match our expect.

[Jiu9Shen]

Try to create a check box on VCF bulk loader page allowing users to choose indel included/excluded.