Call nested mixins with the ">" operator.

In Less, the ">" operator is optional when calling nested mixins but
the Sass conversion needs it.

See http://lesscss.org/features/#mixins-feature-namespaces
Define variables before using them.

In order for Sass compilation to work, variables need to be defined
before they are dereferenced.
Merge branch 'sass-compat' of https://github.com/awood/patternfly into awood-sass-compat
Merge branch 'awood-sass-compat'