docfx serve does not find index.html in percent-encoded directory

[KalleOlaviNiemitalo]

Operating System: Windows

DocFX Version Used: 2.57.2

Template used: None

Steps to Reproduce:

1. MKDIR yleistä
2. ECHO haha>yleistä\index.html
3. docfx serve .
4. Browse to http://localhost:8080/yleist%C3%A4/index.html
5. Note that the Web browser correctly displays haha.
6. Browse to http://localhost:8080/yleist%C3%A4/

Expected Behavior:

7. The Web browser displays haha again.

Actual Behavior:

7. The Web browser displays a directory listing.

Cause:

src/docfx/docfx.csproj references Microsoft.Owin.StaticFiles/3.0.1, which has the bug aspnet/AspNetKatana#371. This has been fixed in Microsoft.Owin.StaticFiles/4.2.0.