Refactor geotogds to no longer use GEOquery::gunzip

[ejh243]

Suggestion in response to issue #17.

Short term solution implemented but adding this as a more extensive solution.

I imagine there is probably a replacement for GEOquery::gunzip as it was labelled as dead code. The solution given in #18 is a minimal solution to the problem that is quick to implement.

A more ideal solution would use the latest version of GEOquery and the geotogds would be refactored to no longer use GEOquery::gunzip.

Originally posted by @sof202 in #17

[sof202]

From the documentation of GEOquery it states:

#' This function was stripped out of R.utils due to breaking some stuff on the
#' bioconductor build machine.

https://github.com/seandavi/GEOquery/blob/7bb80c3ffc3f27fa36dd44a03d4d466b845304b0/R/getGEOfile.R#L142-L143

I'd gander that R.utils has progressed to the point that this is no longer a broken function (and thus R.utils::gunzip can replace GEOquery::gunzip)