Vep runs with same default options as the web tool
other parameters can be specified in the body
allowed alleles include SO terms INS, DEL, TDUP and DUP
offline option not compatible with vep/id endpoint
use cache or database connection where suitable
added vcf example data
add read_cache_info method for all calls
allows compatibility with check_existing option
add check_existing option by default
added documentation for POST vep endpoints
added vep configuration to production file
for GET rsID endpoint, need to modify variation feature object to add 'chr' attribute
also need to add vf slice to slice cache in config