Ease builds on CI and locally (#364)

- react to a smallish breaking change in newer Owin packages
  - add new test of `%` decoding to URI
- do not restore RuntimePortable.sln directly
- ignore binary logs
- ensure the .NET Core 2.1 VS component is installed
  - allow use of any 2.1.5xx .NET SDK
- add a few words to code analysis dictionary
- exclude files generated for `net45` legacy projects don't cause problems when compiling for `netstandard2.0`
- handle additional `ReflectionTypeLoadException`s when using the xUnit `msbuild` runner

nits:
- capitalize "MSBuild" consistently
- reduce indentation slightly

Author: dougbu