use previous version of stylus.

v0.31 breaks existing code due to precision and unit conversion issues.
needs to be better tested before using in production.
Merge pull request #18 from ctalkington/patch5

use previous version of stylus.
Updating to support new this.files property per gruntjs/grunt#606.
Add separator option, warn on nonexistent src files and empty output.
Remove separator option
prep for rc7
Support Stylus import API

Often you want to make some stylus code globally available to your codebase, which the import api facilitates.
Add docs explaining the new  option
Add tests
Titles as links don't look great in markdown

...plus is not consistent with other options.
Add myself to AUTHORS
Merge pull request #24 from jasonkuhrt/patch-1

Support Stylus import API
Reference correct Gruntfile.js
Merge pull request #25 from chrisabrams/master

Reference correct Gruntfile.js
update getting started guide link
0.4 release
add peerDependencies