Patch assembly number with build number from AppVeyor (#3290)

* This should make the AppVeyor build numbers line up with AssemblyInfo, making it easier to relate the version# in the About box with a specific release/tag.

Author: shadowofsilicon

appveyor.yml

@@ -1,4 +1,4 @@
-version: 2.1.{build}
+version: 2.1.{build}-prerelease
 branches:
   only:
   - master
@@ -15,6 +15,10 @@ before_build:
 - ps: choco install innosetup
 build:
   verbosity: normal
+assembly_info:
+  patch: true
+  file: RetailCoder.VBE\Properties\AssemblyInfo.cs
+  assembly_version: '{version}'
 artifacts:
 - path: Installers\Rubberduck.Setup.exe
   name: Rubberduck