Updated to newer libsass

Adding support for passing a precision option to libsass

- Includes some compilation fixes

Testing
----
- Compiled with build-essentials on ubuntu
- Compiled under osx

don't modify the user supplied options object directly

this can cause unindented side-effects if the user uses the same options object for multiple sass calls.

don't prepareOptions twice in `renderFile()`

Doing it twice, once in `renderFile` and then in `render` makes it lose some options.

Fixes sindresorhus/grunt-sass#95

I also made the test actually test includePaths as the current test was faulty.

Drop middleware and examples

Examples been moved to https://github.com/andrew/node-sass-example

Code has now been split out to
https://github.com/andrew/node-sass-middleware

Fixes gh-185

readme - svgify badges

Update install instructions for Ubuntu build issue

add logo - fixes #327

Closes gh-237

Fix ShellJS resolutions on Windows

Relevant to #324

Updated libsass too fix the Windows build

See #318

Update libsass to support BEM style selectors

Upgrade libsass to latest master SHA hash

Added metalsmith-sass to README.md

https://github.com/arturadib/shelljs/issues/41

Tests didn't run on my local machine, however when
checking with the untouched node-sass they didn't
run either with the same errors.

Updated nan to 1.0.0