dev DESCRIPTION PR fix

[mhpob]

Adding back in the changes I accidentally undid when addressing the merge conflict in c3ae7e2.

• Add dplyr to Imports
• Remove plyr from Imports

[jdpye]

I was about to dig into where and how we use sp, it looks like the changeover from greatLakesPoly to great_lakes_poly needs to happen in a few of the vignettes and handouts but nothing in actual package code is implicated. I think we lose sp and fix the vignettes, and possibly in that order.

[mhpob]

I opened #194 for discussion. I removed the sp issue from this PR since it involves some bigger conceptual changes like you've outlined.

[jdpye]

yeah, I think between this PR and #192 we are most of the way home on removing sp