Appveyor: Problem with dependencies

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

Fixes coala#1354

.ci/appveyor.yml

@@ -19,6 +19,8 @@ cache:
   - "node_modules"
   - "C:\\Users\\appveyor\\AppData\\Local\\coala-bears\\coala-bears"
   - "C:\\Users\\appveyor\\AppData\\Roaming\\nltk_data"
+  - '%LocalAppData%\NuGet\Cache'
+  - 'packages -> **\.ci\packages.config'
 
 branches:  # Only build official branches, PRs are built anyway.
   only:
@@ -56,6 +58,8 @@ install:
   - "npm config set loglevel warn"
   - "npm install"
 
+  - "nuget install .ci/packages.config"
+
 build: false  # Not a C# project, build stuff at the test step instead.
 
 test_script:

.ci/packages.config

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+<packages>
+  <package id="libxml2" version="2.7.8.7" targetFramework="net45" developmentDependency="true" />
+  <package id="libxslt" version="1.1.28" targetFramework="net45" developmentDependency="true" />
+  <package id="zlib" version="1.2.8.8 " targetFramework="net45" developmentDependency="true" />
+  <package id="libiconv" version="1.14.0.11" targetFramework="net45" developmentDependency="true" />
+</packages>

bear-requirements.txt

@@ -11,6 +11,7 @@ guess-language-spirit~=0.5.2
 html-linter~=0.3.0
 isort~=4.2
 language-check~=0.8
+lxml==3.6.0
 munkres3~=1.0
 mypy-lang~=0.4.6
 nbformat~=4.1