Update docs on host matching in the `forward` macro
Merge pull request #127 from whatyouhide/forward-with-host-docs

Update docs on host matching in the `forward` macro
Add a bunch of tests to Plug.Conn

Code coverage tools suggested some untested sections of the `Plug.Conn` code.
This commit introduces tests for some of those sections, mainly the ones related
with raising a `Plug.Conn.AlreadySentException` with an already sent connection.
Add other tests to boost the coverage of Conn.Plug
Merge pull request #129 from whatyouhide/plug-conn-coverage

Plug conn coverage
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If you happen to look at stuff on a retina display, you'll thank me for this :).
Merge pull request #130 from whatyouhide/master

SVG Travis badge ftw
Handle struct values when stringifying params
Check struct is an atom for proper type check
Merge pull request #131 from chrismccord/master

Handle struct values when stringifying params
Ensure custom call is always invoked before handle errors
Remove secure:true from Plug.Session ETS example in docs
Fail in Plug.Conn.put_status/2 when the resp had already been sent

Most of the `Plug.Conn` functions raise an `AlreadySentError` when the
response has already been sent. This commit introduces the code and tests that
make this function behave like the others.
Merge pull request #133 from whatyouhide/checks-on-put-status

Fail in Plug.Conn.put_status/2 when the resp had already been sent
docs(README.md): fix typos
Merge pull request #135 from Gazler/docs/readme-typos

docs(README.md): fix typos
Merge pull request #132 from HashNuke/remove-secure-from-ets-example

Remove secure:true from Plug.Session ETS example in docs
Move the Plug.Router.build_host/1 method to Plug.Router.Utils

I move the above-mentioned method to `Plug.Router.Utils` and renamed it to the
more accurate `build_host_match/1`; I also added some doctests.

I also "incidentally" added some explanatory comments to the
`Plug.Router.forward/2` macro.
Merge pull request #138 from whatyouhide/tiny-cleanups

Move the Plug.Router.build_host_match/1 method to Plug.Router.Utils