Fix firefox issue due to capturing events within button element.

[jkmarx]

@hackdna I read comments about firefox having issues capturing events within button elements. Updating to a div fixed it locally without spending too much time on it.

Ref: #3173

[codecov]

Codecov Report

Merging #3185 into develop will decrease coverage by 0.04%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           develop    #3185      +/-   ##
===========================================
- Coverage    62.02%   61.98%   -0.05%     
===========================================
  Files          440      439       -1     
  Lines        27737    27683      -54     
  Branches      1289     1285       -4     
===========================================
- Hits         17205    17160      -45     
+ Misses       10532    10523       -9

Impacted Files	Coverage Δ
refinery/ui/source/js/home/ctrls/home-ctrl.js	75% <0%> (-12.88%)	⬇️
...ery/ui/source/js/home/ctrls/data-set-chart-ctrl.js	61.9% <0%> (-0.17%)	⬇️
...ery/ui/source/js/home/directives/video-carousel.js	52.94% <0%> (-0.13%)	⬇️
...inery/ui/source/js/home/ctrls/twitter-feed-ctrl.js	100% <0%> (ø)	⬆️
.../ui/source/js/home/services/home-config-service.js

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[hackdna]

I think this actually makes more sense since form input of file type is already a button.