Allow extensions

[palcu]

We currently have a way of rejecting resources with a certain extension.

Change the code to support only allowing the current extensions in the website and the following ones for GIS:

•      .cpg
  

•      .dbf
  

•      .prj
  

•      .shp
  

•      .shx
  

•      .qpj
  

[palcu]

And merge the pull request.