Update Appveyor-CI

- Add Ruby-head version
- Remove outdated ruby versions
- Decrease number of ruby versions, so that tests run faster
- Run all tests, even when a test fails
- Make use of Appveyors dual core CPUs

Author: larskanis

appveyor.yml

@@ -1,17 +1,21 @@
 init:
   - SET PATH=C:\Ruby%ruby_version%\bin;%PATH%
-  - SET PATH=C:\MinGW\msys\1.0\bin;%PATH%
   - SET RAKEOPT=-rdevkit
   - SET TESTOPTS='-v'
-  - SET MAKE=make V=1
+  - SET MAKE=make V=1 -j2
 clone_depth: 5
 skip_tags: true
 skip_branch_with_pr: true
 matrix:
-  fast_finish: true
+  fast_finish: false
 install:
   # Output debugging info
   - ps: Update-AppveyorBuild -Version "$(Get-Content $env:appveyor_build_folder\VERSION).$env:appveyor_build_number"
+  - ps: |
+      if ($env:ruby_version -like "*head*") {
+        $(new-object net.webclient).DownloadFile("https://github.com/oneclick/rubyinstaller2/releases/download/rubyinstaller-head/rubyinstaller-$env:ruby_version.exe", "$pwd/ruby-setup.exe")
+        cmd /c ruby-setup.exe /verysilent /dir=C:/Ruby$env:ruby_version
+      }
   - perl --version
   - ruby --version
   - gem --version
@@ -43,13 +47,9 @@ environment:
   TINYTDS_UNIT_AZURE_PASS:
     secure: fYKSKV4v+36OFQp2nZdX4DfUpgmy5cm0wuR73cgdmEk=
   matrix:
-    - ruby_version: "23-x64"
-    - ruby_version: "23"
-    - ruby_version: "24-x64"
     - ruby_version: "24"
     - ruby_version: "25-x64"
-    - ruby_version: "25"
-    - ruby_version: "26-x64"
     - ruby_version: "26"
+    - ruby_version: "head-x64"
 on_failure:
   - find -name compile.log | xargs cat