AppveyorCI: Prevent skip of tests of XMLBear

XMLBear is skipped on Appveyor Windows builds
due to dependency issues. Fixes all dependency
issues.

Closes #1354

.ci/appveyor.yml

@@ -30,7 +30,7 @@ install:
   # done from inside the powershell script as it would require to restart
   # the parent CMD process).
   - "SET PATH=%PYTHON%;%PYTHON%\\Scripts;%PATH%"
-  - "SET PATH=C:\\Program\ Files\\Java\\jdk1.7.0\\bin;%PATH%"
+  - "SET PATH=C:\\tools\\xmllint\\bin;C:\\Program\ Files\\Java\\jdk1.7.0\\bin;%PATH%"
 
   # language-tool needs the registry tweaked here since it determines the java
   # version wrong (since appveyor has both, 1.7 and 1.8 in x86 and x64).
@@ -49,6 +49,9 @@ install:
   - "npm config set loglevel warn"
   - "npm install"
 
+  - "wget ftp://ftp.zlatkovic.com/libxml/*.win32.zip"
+  - "7z x *.zip -oC:\\tools\\xmllint"
+
 build: false  # Not a C# project, build stuff at the test step instead.
 
 test_script: