Update pepa and st4gi in the server

[omarbenites]

The pepa and st4gi package have been modified to include new functionalities like n-factorials:

• [ ] Update st4gi package
• [ ] Migrate .Rmd files to the server environment. (sweetpotatobase and agrofims www folders)
• [ ] Change the code of statistical reports in sweetpotatobase. (single_analysis_sbase.R)
• [ ] Change the code of statistical reports in agrofims. (single_analysis_agrofims.R)