Update test/README.md about sharness directory

Now sharness is in "lib/sharness"

Add test script for block command

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

Add more documentation to ipfs

Update random for test/

There is a dummy test import: test/lib/random-dep.go
Because godep doen't yet vendor binaries nicely.

I moved installed things into own dirs bin and lib.

@chriscool sorry to move things around again, the top level
test dir was getting a bit clutterd.

prevent NAT check if given nil multiaddr

Install sharness

It is cleaner if sharness is installed in its own
directory.

Install sharness + add to tests to coverage

Addresses comments in: https://github.com/jbenet/go-ipfs/commit/7e14f1737d146cb45f3d788f229dae9fd964e524

The tests were using the globally installed ipfs.
This commit changes it to build + use its own ipfs binary.

When there is no fuse we should skip all mount
tests and using a FUSE prerequisite is a good
way to do that.