(feat) Add the repository url to cargo

This will allow crates.io to show a link to the repository at the bottom of iron's page.
Merge pull request #235 from Darayus/patch-1

Add the repository url to cargo
(fix) Fixes a misuse of the Host header that led to bogus urls.

Fixes #234
Merge pull request #236 from reem/fix-host

(fix) Fixes a misuse of the Host header that led to bogus urls.
(release) Release 0.0.4.