Connect to ENCODE

[bschilder]

Add API to import data from ENCODE directly.
DeepBlueR seems like a good candidate package to do this, but is extremely complicated to use:
https://www.bioconductor.org/packages/devel/bioc/vignettes/DeepBlueR/inst/doc/DeepBlueR.html

[bschilder]

Now handled by PeakyFinders, but needs to be integrated into echoverse.
https://github.com/neurogenomics/PeakyFinders