return connected peers as providers

dialing 4000 connections somehow keeps choking both travis and
jenkins. dialing this down to 500

http://gateway.ipfs.io/ipfs/QmfUFkQuqjfQzLNhMLwiibiAxnAaZEJAbYkey9orXJ4aQe/3lcat.jpg

add more help text for ipfs diag net

Gateway Changes

cc @mappum

core/corehttp: gateway_handler: Redirect to path with trailing slash when showing a directory's index.html

- attempts set to 1 now.
- timeouts must account for that.

fuse: no longer require fuse to compile ipfs

This commit removes the dependency on go-fuse-version, and thus the
fuse headers. It also introduces an elaborate troubleshooting process
that diagnoses whether fuse installed -- and which version -- with as
little requirements as possible (attept to use sysctl, fall-back on
the go-fuse-version binary, etc). It then nicely instructs the user
what to do next.

p2p/net: dial log -> events

+ fixed race

Allow sharness to run daemon without FUSE

cc @whyrusleeping: you werent doing so
cc @mappum: you were trying to escape them, but
   were un-escaping them in cases with longer quotes.

In OSX, the `echo -n` was _somehow_ printing "-n" out... not
really sure why, as the bsd `echo` program supports -n. I changed
this to printf -- which is safer.

Let's use `>file`, not `> file`, as it makes it easier to parse.

This commit allows sharness tests to run daemon tests when the FUSE
option is off. Unsure why this was previously included.

Fix daemon initialization output change