Release candidate vibe.d 0.8.0-rc.5

[Sönke Ludwig via Digitalmars-d-announce]

- Fixes a regression where HTTPClientRequest.writeFormBody started to 
use chunked transfer encoding.
- Fixed building on win32/mscoff when not specifying and explicit 
configuration for vibe-d:core
- Works around an issue where it was not possible anymore to compile 
vibe.d without OpenSSL support

Release is rescheduled for next Monday (10nth of July).