demo: switch logo png -> svg
demo: switch logo png -> svg

Our logo in the png format is not optimized but
even after optimization it would be larger than svg.
On top of this SVG looks better so let's switch!

Closes #936

benouat/ng-bootstrap,Xaiid/ng-bootstrap,johnbenz13/ng-bootstrap,deeg/ng-bootstrap,benouat/ng-bootstrap,benouat/ng-bootstrap,maxokorokov/core,fbasso/ng-bootstrap,ktriek/ng-bootstrap,ktriek/ng-bootstrap,spongessuck/ng-bootstrap,johnbenz13/ng-bootstrap,fbasso/ng-bootstrap,Foxandxss/ng-bootstrap,jnizet/ng-bootstrap,deeg/ng-bootstrap,ktriek/ng-bootstrap,spongessuck/ng-bootstrap,Xaiid/ng-bootstrap,ACGC/ng-bootstrap,jnizet/ng-bootstrap,chenyuzhcy/ng-bootstrap,fbasso/ng-bootstrap,ng-bootstrap/ng-bootstrap,ng-bootstrap/core,pkozlowski-opensource/core,maxokorokov/core,CrustyJew/ng-bootstrap,CrustyJew/ng-bootstrap,ktriek/ng-bootstrap,chenyuzhcy/ng-bootstrap,jnizet/ng-bootstrap,pkozlowski-opensource/core,mschoudry/ng-bootstrap,deeg/ng-bootstrap,mschoudry/ng-bootstrap,deeg/ng-bootstrap,chenyuzhcy/ng-bootstrap,benouat/ng-bootstrap,spongessuck/ng-bootstrap,jnizet/ng-bootstrap,spongessuck/ng-bootstrap,mschoudry/ng-bootstrap,Foxandxss/ng-bootstrap,ng-bootstrap/core,ACGC/ng-bootstrap,ACGC/ng-bootstrap,maxokorokov/core,Xaiid/ng-bootstrap,CrustyJew/ng-bootstrap,ng-bootstrap/ng-bootstrap,CrustyJew/ng-bootstrap,fbasso/ng-bootstrap,pkozlowski-opensource/core,maxokorokov/core,ng-bootstrap/ng-bootstrap,ng-bootstrap/core,johnbenz13/ng-bootstrap,ng-bootstrap/ng-bootstrap,Foxandxss/ng-bootstrap