We are getting errors from the opencover command, fixing it

Author: cprieto

runtests.ps1

@@ -10,12 +10,10 @@ $filter = "-filter:+[SimpleConf*]* -[SimpleConf.Tests*]*"
 &$opencover $target $targetargs -register:user $filter -output:coverage.xml
 
 If (Test-Path env:APPVEYOR) {
-    $coverage_result = Get-ChildItem -Filter coverage.xml -Recurse | Resolve-Path -Relative
-    $coverall_args = "--opencover $coverage_result -r $env:COVERALL_TOKEN"
-    $coverall = (Get-ChildItem -Filter "coverall.net.exe" -Recurse | Resolve-Path -Relative).FullName
+    $coverage_file = (Get-ChildItem -Filter coverage.xml -Recurse).FullName
+    $coveralls = (Get-ChildItem -Filter "coveralls.net.exe" -Recurse).FullName
 
-    &$coverall $coverall_args 
+    &$coveralls `--opencover $coverage_file `-r $env:COVERALL_TOKEN
 } else {
-    Write-Host -ForegroundColor Green "Not running in CI"
-}
-
+    Write-Host -ForegroundColor Green "Not running in CI, skipping upload of coverage data"
+}