devtools::install_github() - Ignore SSL cert verification failure
One way to handle the problem is to set the CURLOPT_SSL_VERIFYPEER to false. This option determines whether curl verifies the authenticity of the peer's certificate. A value of 1 means curl verifies; 0 (zero) means it doesn't.http://curl.haxx.se/libcurl/c/CURLOPT_SSL_VERIFYPEER.html
The relevant option needs to be passed to RCurl. In RCurl the CURLOPT_ is removed letters arre lowercase and the underscore is changed to ..
set_config( config( ssl.verifypeer = 0L ) )will pass the relevant option to RCurl when using httr.
UPDATE:
The httr since this answer was written has moved from RCurl as an underlying dependence to the curl package. cURL options are now specified with underscores so the above would be:
set_config( config( ssl_verifypeer = 0L ) )in the current version of httr.
I tired @jdharrisonbut method but it didn't worked for me.
A Quick fix to avoid using https connection, is by replacing https by http. you install a package from cran by this method.
install.packages("http://cran.r-project.org/src/contrib/ggvis_0.4.4.tar.gz", repo=NULL, type="source")