[ENHANCEMENT] Make the possibility to use transcriptomes from VectorBase

[livisupajares]

I'm currently working on a project where I need to find targets from Aedes aegypti and Aedes albopictus' miRNAs. I saw your code, and I can see that you only used ensembl transcriptomes to make 3'UTR annotations. Unfortunately, the Aedes species mentioned aren't found on ensembl. This is why I am asking if it's possible to add an option to fetch the transcriptomes from Aedes aegypti and Aedes albopictus, whose transcriptomes are only found on VectorBase.

I know Aedes albopictus doesn't have miRNAs predicted on miRBase. However, it is very easy to add those miRNAs sequences since I already have them.