Change meta headers to pass vcftools perl module parser

vcftools Vcf.pm doesn't parse lines like:

##INPUT=<bcf=-,ped=/lustre/scratch113/projects/ddd/users/ddd/dng_run_2014-07-28/DDDP107728/dng/trio.ped>

Change to:
##input_bcf=-
##input_ped=trio.ped