add readlink

Disable the test on a symbolic link until symlink is added.

Also add myself to AUTHORS
add symlink

Also enable readlink's symbolic link test.
make find_node symbolic link aware

This adds a new constant SYMLOOP_MAX, which corresponds to the POSIX
variable of the number of symbolic links that may be followed. A new
error Eloop was added to signal when SYMLOOP_MAX is exceeded.
SYMLOOP_MAX has been arbitrarily set to 10 while on linux it is set
to 40 and the POSIX minimum is 8.

find_node when encountering a symbolic link anywhere in the given path
will attempt to follow it.

Note that SYMLOOP_MAX is only the limit of symbolic links to
follow per symbolic link. There is currently no attempt to limit
the total number of symbolic links followed when resolving a path.

This adds tests for path resolution of symbolic links as well.
add lstat
test stat's symbolic link support
test readdir's symbolic link support
rmdir should error on non-directories
test link should not follow symbolic links
unlink should not follow symbolic links
unlink_node - add missing var
open should follow symbolic links

This functionality is tested implicitly through tests in
writefile, readfile
test rename does not follow symbolic links
Merge pull request #38 from ispedals/symbolic-link

Initial Implementation of Symbolic link
Make backends pluggable via FileSystem ctor, fixes #36.
Review fixes
Merge pull request #39 from humphd/issue36

Make backends pluggable via FileSystem ctor, fixes #36.
update build
Initial tests from node repo
Working null byte patch checks
Switch to node.js' callback pattrn, update public API to match node.js