Try to fix appimage cert issues.

appveyor.yml

@@ -85,6 +85,7 @@ for:
       - mv library.bin AppDir/usr/share/leocad/library.bin
       - cp qt/leocad.desktop AppDir/leocad.desktop
       - cp tools/icon/256x256/apps/leocad.png AppDir/leocad.png
+      - cp tools/setup/AppRun AppDir
       - appveyor DownloadFile https://github.com/probonopd/linuxdeployqt/releases/download/continuous/linuxdeployqt-continuous-x86_64.AppImage
       - chmod a+x linuxdeployqt*.AppImage 
       - unset QTDIR; unset QT_PLUGIN_PATH ; unset LD_LIBRARY_PATH

tools/setup/AppRun

@@ -0,0 +1,27 @@
+#!/bin/bash -e
+
+this_dir="\$(readlink -f "\$(dirname "\$0")")"
+unset QTDIR; unset QT_PLUGIN_PATH
+
+# Find the system certificates location
+# https://gitlab.com/probono/platformissues/blob/master/README.md#certificates
+possible_locations=(
+    "/etc/ssl/certs/ca-certificates.crt"                # Debian/Ubuntu/Gentoo etc.
+    "/etc/pki/tls/certs/ca-bundle.crt"                  # Fedora/RHEL
+    "/etc/ssl/ca-bundle.pem"                            # OpenSUSE
+    "/etc/pki/tls/cacert.pem"                           # OpenELEC
+    "/etc/ssl/certs"                                    # SLES10/SLES11, https://golang.org/issue/12139
+    "/usr/share/ca-certs/.prebuilt-store/"              # Clear Linux OS; https://github.com/knapsu/plex-media-player-appimage/issues/17#issuecomment-437710032
+    "/system/etc/security/cacerts"                      # Android
+    "/etc/pki/ca-trust/extracted/pem/tls-ca-bundle.pem" # CentOS/RHEL 7
+    "/etc/ssl/cert.pem"                                 # Alpine Linux
+)
+
+for location in "\${possible_locations[@]}"; do
+    if [ -r "\${location}" ]; then
+    export SSL_CERT_FILE="\${location}"
+    break
+    fi
+done
+
+exec "\${this_dir}/usr/bin/leocad" "\$@"