modify ie7 width function to operate through a variable, rather than a mixin
add push and pull functionality
update to variable for expression based widths
update to readme
add spacing to be consistent
Merge pull request #15 from timjgleeson/feature/push-pull

add push and pull functionality
Merge remote-tracking branch 'upstream/master' into feature/clean-ie7
Merge pull request #14 from timjgleeson/feature/clean-ie7

A cleaner IE7 implementation
0.0.4