Hello all, 

The ensembl 90 gtf (converted to GRanges on the fly) and fasta (twobit files) been added to AnnotationHub and are currently available in Bioc3.6 (development) 

> hub = AnnotationHub()
snapshotDate(): 2017-08-28
> length(query(hub, c("ensembl", "gtf", "release-90")))
[1] 248
> length(query(hub, c("fasta", "release-90", "twobit"))) 
[1] 413