Add jsonlite to getSupportedGenomes method

[vladimirobucina]

If someone is using rjson library as a default for fromJSON function this line of code won't work:
https://github.com/paul-shannon/igvR/blob/26e99bdbe054e3c005d24745a090c6c3cc944e0b/R/igvR.R#L319

It should say:
tbl.genomes <- jsonlite::fromJSON(current.genomes.raw)

[gladkia]

Hi @vladimirobucina. Thanks for the suggestion.
FYI, igvR uses wrapper of fromJSON with auto_unbox set by default to TRUE (link1, link2). More details can be found here.