Deal with SCSS deprecation warnings

[lmullen]

I get these deprecation warnings:

DEPRECATION WARNING on line 115 of /Users/lmullen/github/religious-ecologies/website/node_modules/foundation-sites/scss/util/_color.scss:
!global assignments won't be able to declare new variables in future versions.
Consider adding `$primary-color: null` at the top level.

DEPRECATION WARNING on line 120 of /Users/lmullen/github/religious-ecologies/website/node_modules/foundation-sites/scss/util/_color.scss:
!global assignments won't be able to declare new variables in future versions.
Consider adding `$secondary-color: null` at the top level.

DEPRECATION WARNING on line 125 of /Users/lmullen/github/religious-ecologies/website/node_modules/foundation-sites/scss/util/_color.scss:
!global assignments won't be able to declare new variables in future versions.
Consider adding `$success-color: null` at the top level.

DEPRECATION WARNING on line 130 of /Users/lmullen/github/religious-ecologies/website/node_modules/foundation-sites/scss/util/_color.scss:
!global assignments won't be able to declare new variables in future versions.
Consider adding `$warning-color: null` at the top level.

DEPRECATION WARNING on line 135 of /Users/lmullen/github/religious-ecologies/website/node_modules/foundation-sites/scss/util/_color.scss:
!global assignments won't be able to declare new variables in future versions.
Consider adding `$alert-color: null` at the top level.

DEPRECATION WARNING on line 164 of /Users/lmullen/github/religious-ecologies/website/node_modules/foundation-sites/scss/util/_breakpoint.scss:
!global assignments won't be able to declare new variables in future versions.
Consider adding `$-zf-size: null` at the top level.

DEPRECATION WARNING on line 369 of /Users/lmullen/github/religious-ecologies/website/node_modules/foundation-sites/scss/util/_mixins.scss:
!global assignments won't be able to declare new variables in future versions.
Consider adding `$-zf-bp-value: null` at the top level.

[hepplerj]

After a bit of research this morning, it appears this is a known issue in foundation-sites v6, and there are plans--though not a clear roadmap--for version 7 (see #11847). Foundation is no longer actively maintained by ZURB developers and has been turned over to open source volunteers.

Their focus seems to be on version 7 and a timeline on maintenance seems uncertain, so I'd recommend we make a simple change to app.scss to set those !global declarations to null as suggested in the depreciation warnings. I'll push an update for those shortly.

I'd also say let's keep this issue open for now and I'll keep an eye on things over at foundation-sites in the event an update comes from them.