Use compass mixins when possible

[ericdfields]

Since the name of the project assumes a dependency on compass, why not cut down on some code by using pre-existing mixins for things like box-shadow instead of emulating twitter's less functions?

I did the same in another port, not realizing this one was already so mature ;-) https://github.com/hecbuma/compass-bootstrap

[vwall]

That's how this project started out, I was just in a hurry to push out 2.0. I would like to make the parser do this. It's really no fun doing it by hand.

[aaronchi]

Yep. default compass box-shadow mixin is getting overwritten and causing problems.

[wyuenho]

background-size is getting overwritten too. It maybe wise to prefix all compass-twitter-bootstrap mixins mixin includes to avoid future name conflicts again.

[tijsverkoyen]

see #87

[ldexterldesign]

Ditto, comment out the Compass Bootstrap box-shadow() @mixin and revert back to Compass' version, which works.

Hope to see this fixed in the next release.

Kind regards,

PS Love you work here on the port - keep it up!