User defined VCF header

[fgvieira]

When querying a database, would it be possible to add an option so the user can define the VCF header? Right now it always says:

##INFO=<ID=XXX_AN,Number=1,Type=Integer,Description="The number of occurances of the event in the database">
##INFO=<ID=XXX_AF,Number=1,Type=Float,Description="The frequency of the event in the database">

But it would be nice to be able to add custom labels to include more information, like which database (and which version) was used.