Add overwrite arg to downloadModule & downloadData

[eliotmcintire]

@CeresBarros suggested an overwrite argument. It would have to be passed through to GET to httr::write_disk which actually does the writing to disk.

Perhaps like this:
(https://yokekeong.com/download-files-over-https-in-r-with-httr/)

e.g.,

    library(httr)
    url <- "https://rawgit.com/yoke2/dsxref/master/iris.xlsx"
    GET(url, write_disk("iris.xlsx", overwrite=TRUE))

[achubaty]

NOTE: download.file already overwrites by default

[eliotmcintire]

presumably a FALSE is also relevant, thus the need for argument

[achubaty]

Yes. Sorry my “note to self” wasn't fully explanatory: we will need to rewrite the uses of download.file to use GET so that an overwrite arg can be passed everywhere relevant.

[CeresBarros]

I've added an overwrite option to downloadModule and opened a PR. There seem to be two minor conflicts (which I think I solved?) on the .R and .Rd files for downloadModules.
I've also tried to clarify the documentation of getModuleVersion, as I felt it wasn't clear where the version was being extracted from.

[CeresBarros]

Also, in response to Alex's last comment: are you sure the overwrite option can be passed to GET? I've passed if to write_disk in downloadModule, because I couldn't find an overwrite option in GET.

[achubaty]

Thanks @CeresBarros! The overwrite arg is passed to write_disk inside the GET call; see the example Eliot used in the first message in this thread. It sounds like you used it correctly. I'll review the PR later tonight.

[achubaty]

@CeresBarros did you also add it to downoladData?

[CeresBarros]

Nop, but if overwrite passes from GET to write_disk I'll do it :)