Set global variable explicitly

Fixes:

```
DEPRECATION WARNING on line 85 of test/test.scss:
Assigning to global variable "$mq-breakpoints" by default is deprecated.
In future versions of Sass, this will create a new local variable.
If you want to assign to the global variable, use "$mq-breakpoints: mq-add-breakpoint(cinema, 4096px) !global" instead.
```
Bump version
Use Sass 3.3 Maps instead of lists - fixes #5
Update readme with Maps notation
Specify the right version in bower.json
Ability to show active breakpoint in corner of viewport

Thanks to @bewildergeist - see #7
Bump to version 2.0.0-rc.2
Set breakpoints to Guardian Next Gen defaults
Update bower.json
We're in 2014
Merge branch 'sass33'

Conflicts:
	README.md
	bower.json
	test/test.css
	test/test.scss