restraintd: fetch_http premature error cleanup fix

Fixed premature error cleanup for http fetcher.
restraintd: https support

Libsoup supports https but restraintd accepted http uris only, changed the
if statement to accept both.
Merge pull request #23 from sm00th/https_segfault

https segfault fix
Merge pull request #24 from p3ck/client_multipart

Client multipart
Clear error in recipe_handler_finish

Previously error was being cleared before we closed our connection to
the client which prevented us from propagating that error.
client post multipart fixes
server post multipart fixes