Update README.md
update mime.rs dependency url
add Headers.set_raw, remove unsafe from .get_raw

Internal representation was changed from an enum back to a Struct again.
The raw representation *has* to stick around, even if parsed as a proper
typed header. The reason is that internally, hyper will access some
headers to know which parts of the http protocol to follow (such as if
the response has a length or is chunked). The raw value may still be
needed afterwards, such as for a DOM binding of
.getAllResponseHeaders().

Since the raw is kept around, the unsafety of get_raw is no longer true,
and so that is removed.

It's still more ergonomic to access the types, and safer as well, so
that is recommended when possible.
Merge pull request #70 from hyperium/raw

add Headers.set_raw, remove unsafe from .get_raw
add bits to deal with Upgrade requests
(fix) fail! to panic!
Merge pull request #91 from hyperium/fix/fail-to-panic

(fix) fail! to panic!
Merge pull request #59 from hyperium/upgrade

add bits to deal with Upgrade requests
Split Header into Header and HeaderFormat

Header contains all of the trait-object unsafe methods
including the name of the header and parsing. HeaderFormat
contains fmt_header, which is the only trait-object safe
method.
Update all common headers for the new Header trait split
Merge pull request #92 from reem/header-trait-split

Split Header into Header and HeaderFormat
split NetworkStream::connect to NetworkConnector
fix missing_docs lint name
update benches with trait splits
Merge pull request #93 from hyperium/split-networkstream

split NetworkStream::connect to NetworkConnector
Remove collections trait implementations.

Rust has removed them due to collections reform RFC:

RFC: https://github.com/rust-lang/rfcs/pull/235/files
Commit:
https://github.com/rust-lang/rust/commit/21ac985af44f4e2470ef6f4c0eb4d72daf5a6497
Re-add len() and clear() as inherent Headers methods.
Add len() test with redundant header.
Merge pull request #95 from jamwt/remove_coll_traits

Move len/clear from trait implementations to inherent methods
Update hash_map and fmt usages

Depends on https://github.com/carllerche/curl-rust/pull/24 and
https://github.com/chris-morgan/rust-http/pull/167