remove dialer from GCR client

this might solve all our problems

fix for #757

have repo tilde expand paths

gateway: attempt to resolve hostname to ipfs path

fix a panic caused by context cancelling closing a promise channel

Fixed 'ipfs block put' panic

implement nodebuilder

p2p/net/conn: respect context on dialing

We were half-way with this. there's no way for net.Dialers
to respect contexts, so we have to let the dial finish in
the background.

document some packages

ctx.Done fixes

thanks @whyrusleeping for finding these.

Use multihash not shasum

License: MIT
Signed-off-by: Kevin Wallace <kevin@pentabarf.net>

License: MIT
Signed-off-by: Kevin Wallace <kevin@pentabarf.net>

This allows someone to host a static site by pointing a TXT record at their
content in IPFS, and a CNAME record at an IPFS gateway.

Note that such a setup technically violates RFC1912 (section 2.4; "A CNAME
record is not allowed to coexist with any other data."), but tends to work in
practice.

We may want to consider changing the DNS->IPFS resolution scheme to allow this
scenario to be RFC-compliant (e.g. store the mapping on a well-known subdomain
to allow CNAME records on the domain itself).

License: MIT
Signed-off-by: Kevin Wallace <kevin@pentabarf.net>

Each option now additionally returns the mux to be used by future options. If
every options returns the mux it was passed, the current behavior is unchanged.

However, if the option returns an a new mux, it can mediate requests to handlers
provided by future options:

    return func(n *core.IpfsNode, mux *http.ServeMux) (*http.ServeMux, error) {
      childMux := http.NewServeMux()
      mux.Handle("/", handlerThatDelegatesToChildMux)
      return childMux, nil
    }

License: MIT
Signed-off-by: Kevin Wallace <kevin@pentabarf.net>

License: MIT
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>

As shasum is not installed on all machines and
we use multihash anyway in the code base, it
removes one dependency to use shasum instead of
shasum in the tests.

Now that there are sharness tests in multihash
it is also safe to use it.

License: MIT
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>

go-multihash update

gateway: dont cache ipns paths

ipns paths are mutable and should not be cached. this error is
a byproduct of the currently messy gateway route. We should split
the /ipfs and /ipns routes up.

ratelimiter: fixing rate limiter use

Use of the ratelimiter should be conscious of the ratelimiter's
potential closing. any loops that add work to ratelimiter
should (a) only do so if the rate limiter is not closed,
or (b) prevent limiter while work is added
(i.e. use limiter.Go(addWorkHere))

since construction can fail, and construction is non-trivial, it's
probably safer to never assume resource exists.

cc @jbenet @whyrusleeping